Use ActiveJob 5.2 retry logic for old jobs

Deprecate `where.not` working as NOR and will be changed to NAND in Rails 6.1

[Matilda Smeds & Xavier Noria]

This commit more or less undoes 9b5401fc, restores autoloaded? not to
touch the descendants tracker, and autoloaded_constants because it is
documented in the guide.

Rails 6 introduces retries per-exception, instead of a global count of
retries. Because ActiveJob 5.2 doesn't serialize the execution count
per-exception, when ActiveJob 6.0 picks up an "old" job it can't know
the exception count in the new format.

This can also be an issue if AJ 6.0 serializes a new job with
exception_executions which is later picked up by AJ 5.2, which would
clear exception_executions (since it has no knowledge of it).

Previously we handled this by resetting exception_executions, if it
wasn't defined on a job, which could result in the worst case retrying
the job 2x the times we should.

This commit changes how we handle loading a legacy job: instead of
resetting exception_executions, we instead will always use the global
executions count.

This way, jobs which only have one retry_on (and didn't have a behaviour
change in AJ 6) are backwards-and-forwards-compatible with counts
respected exactly.

Jobs with multiple retry_on will revert to the AJ5.2 behaviour if they
were ever run under AJ5.2.

Revert "Include Caching module for ActionController::API"

Include Caching module for ActionController::API

In Rails updating an Active Storage relation will now replace the entire
association instead of merely adding to it.
https://github.com/rails/rails/issues/35817#issuecomment-485512520

Fixes #35817

cc @georgeclaghorn

- Allow configuring the sanitizer and its options
- Split attachment rendering and sanitizing helpers so each can be overridden by applications

Support all Redis features without needing to maintain a list of valid options that must stay in sync with the upstream client library.

Related 0ee96d13.

PERF: 20% faster pk attribute access

Update changelog to explain the fix of #35114 [ci skip] 

Make system tests take failed screenshots in `before_teardown` hook

Those helper methods makes relation values access 15% slower.

https://gist.github.com/kamipo/e64439f7a206e1c5b5c69d92d982828e

Before (02b5b8cb):

```
Warming up --------------------------------------
        #limit_value   237.074k i/100ms
    #limit_value = 1   222.052k i/100ms
Calculating -------------------------------------
        #limit_value      6.477M (± 2.9%) i/s -     32.479M in   5.019475s
    #limit_value = 1      5.297M (± 4.3%) i/s -     26.424M in   4.999933s
```

After (this change):

```
Warming up --------------------------------------
        #limit_value   261.109k i/100ms
    #limit_value = 1   239.646k i/100ms
Calculating -------------------------------------
        #limit_value      7.412M (± 1.6%) i/s -     37.077M in   5.003345s
    #limit_value = 1      6.134M (± 1.0%) i/s -     30.675M in   5.000908s
```

I've realized that `user.id` is 20% slower than `user.name` in the
benchmark (https://github.com/rails/rails/pull/35987#issuecomment-483882480).

The reason that performance difference is that `self.class.primary_key`
method call is a bit slow.

Avoiding that method call will make almost attribute access faster and
`user.id` will be completely the same performance with `user.name`.

Before (02b5b8cb):

```
Warming up --------------------------------------
             user.id   140.535k i/100ms
          user['id']    96.549k i/100ms
           user.name   158.110k i/100ms
        user['name']    94.507k i/100ms
       user.changed?    19.003k i/100ms
 user.saved_changes?    25.404k i/100ms
Calculating -------------------------------------
             user.id      2.231M (± 0.9%) i/s -     11.243M in   5.040066s
          user['id']      1.310M (± 1.3%) i/s -      6.565M in   5.012607s
           user.name      2.683M (± 1.2%) i/s -     13.439M in   5.009392s
        user['name']      1.322M (± 0.9%) i/s -      6.615M in   5.003239s
       user.changed?    201.999k (±10.9%) i/s -      1.007M in   5.091195s
 user.saved_changes?    258.214k (±17.1%) i/s -      1.245M in   5.007421s
```

After (this change):

```
Warming up --------------------------------------
             user.id   158.364k i/100ms
          user['id']   106.412k i/100ms
           user.name   158.644k i/100ms
        user['name']   107.518k i/100ms
       user.changed?    19.082k i/100ms
 user.saved_changes?    24.886k i/100ms
Calculating -------------------------------------
             user.id      2.768M (± 1.1%) i/s -     13.936M in   5.034957s
          user['id']      1.507M (± 2.1%) i/s -      7.555M in   5.017211s
           user.name      2.727M (± 1.5%) i/s -     13.643M in   5.004766s
        user['name']      1.521M (± 1.3%) i/s -      7.634M in   5.018321s
       user.changed?    200.865k (±11.1%) i/s -    992.264k in   5.044868s
 user.saved_changes?    269.652k (±10.5%) i/s -      1.344M in   5.077972s
```

It was never used from the beginning.

ActiveStorage - normalize the hash of transformations

Allow ActiveStorage to generate variants of BMP images

Avoid method call if `@transaction_state` is not finalized

Method call in Ruby is a bit slow.

This makes attribute access 10% faster by avoiding method call
(`sync_with_transaction_state`).

Before (96cf7e0e):

```
Warming up --------------------------------------
             user.id   131.291k i/100ms
          user['id']    91.786k i/100ms
           user.name   151.605k i/100ms
        user['name']    92.664k i/100ms
       user.changed?    17.772k i/100ms
 user.saved_changes?    23.909k i/100ms
Calculating -------------------------------------
             user.id      1.988M (± 7.0%) i/s -      9.978M in   5.051474s
          user['id']      1.155M (± 5.8%) i/s -      5.783M in   5.022672s
           user.name      2.450M (± 4.3%) i/s -     12.280M in   5.021234s
        user['name']      1.263M (± 2.1%) i/s -      6.394M in   5.066638s
       user.changed?    175.070k (±13.3%) i/s -    853.056k in   5.011555s
 user.saved_changes?    259.114k (±11.8%) i/s -      1.267M in   5.001260s
```

After (this change):

```
Warming up --------------------------------------
             user.id   137.625k i/100ms
          user['id']    96.054k i/100ms
           user.name   156.379k i/100ms
        user['name']    94.795k i/100ms
       user.changed?    18.172k i/100ms
 user.saved_changes?    24.337k i/100ms
Calculating -------------------------------------
             user.id      2.201M (± 0.5%) i/s -     11.010M in   5.002955s
          user['id']      1.320M (± 1.0%) i/s -      6.628M in   5.021293s
           user.name      2.677M (± 1.6%) i/s -     13.449M in   5.024399s
        user['name']      1.314M (± 1.8%) i/s -      6.636M in   5.051444s
       user.changed?    190.588k (±11.1%) i/s -    944.944k in   5.065848s
 user.saved_changes?    262.782k (±12.1%) i/s -      1.290M in   5.028080s
```

Fix typo by changing 'for' to 'from'

Previously we were calling the `take_failed_screenshot` method in an
`after_teardown` hook. However, this means that other teardown hooks
have to be executed before we take the screenshot. Since there can be
dynamic updates to the page after the assertion fails and before we
take a screenshot, it seems desirable to minimize that gap as much as
possible. Taking the screenshot in a `before_teardown` rather than an
`after_teardown` helps with that, and has a side benefit of allowing
us to remove the nested `ensure` commented on here:
https://github.com/rails/rails/pull/34411#discussion_r232819478

Change the deprecation message for dynamic routes segment to 6.1

[#35782] Allow loading seeds without ActiveJob (~> 5.2.3)

ActiveJob time argument assertion documentation

With 8b4d3448, `test_required_polymorphic_belongs_to_generates_correct_model`
and `test_required_and_polymorphic_are_order_independent` are completely
same. Also, remove `required` from test name because that not passed to
generator.

This was accidentally left in, the standard `db:migrate:up` doesn't have
a description so `db:migrate:up:namespace` shouldn't have one either.

Handle up/down for multiple databases

This change adds the ability to run up/down for a database in a multi-db
environment.

If you have an app with a primary and animals database the following
tasks will be generated:

```
VERSION=123 rake db:migrate:up:primary
VERSION=123 rake db:migrate:up:primary

VERSION=123 rake db:migrate:down:primary
VERSION=123 rake db:migrate:up:animals
```

I didn't generate descriptions with them since we don't generate a
description for a single database application.

In addition to this change I've made it so if your application has
multiple databases Rails will raise if you try to run `up` or `down`
without a namespace. This is because we don't know which DB you want to
run `up` or `down` against unless the app tells us, so it's safer to
just block it and recommend using namespaced versions of up/down
respectively.

The output for the raise looks like:

```
You're using a multiple database application. To use `db:migrate:down`
you must run the namespaced task with a VERSION. Available tasks are
db:migrate:down:primary and db:migrate:down:animals.
```