The lack of ability for making this has resolved by #39496 and #39530.

Support `where` with comparison operators (`>`, `>=`, `<`, and `<=`)

`PredicateBuilder.references` and `PredicateBuilder#build_from_hash`
does similar processing and both requires stringify keys for passed hash
argument. This consolidates stringify keys to avoid extra string
allocation in `PredicateBuilder`.

```ruby
posts = Post.order(:id)

posts.where("id >": 9).pluck(:id)  # => [10, 11]
posts.where("id >=": 9).pluck(:id) # => [9, 10, 11]
posts.where("id <": 3).pluck(:id)  # => [1, 2]
posts.where("id <=": 3).pluck(:id) # => [1, 2, 3]
```

From type casting and table/column name resolution's point of view,
`where("create_at >=": time)` is better alternative than `where("create_at >= ?", time)`.

```ruby
class Post < ActiveRecord::Base
  attribute :created_at, :datetime, precision: 3
end

time = Time.now.utc # => 2020-06-24 10:11:12.123456 UTC

Post.create!(created_at: time) # => #<Post id: 1, created_at: "2020-06-24 10:11:12.123000">

# SELECT `posts`.* FROM `posts` WHERE (created_at >= '2020-06-24 10:11:12.123456')
Post.where("created_at >= ?", time) # => []

# SELECT `posts`.* FROM `posts` WHERE `posts`.`created_at` >= '2020-06-24 10:11:12.123000'
Post.where("created_at >=": time) # => [#<Post id: 1, created_at: "2020-06-24 10:11:12.123000">]
```

This has had no effect since 771a802c.

Error entries appear in the log when we request ActiveStorage
controllers (`ActiveStorage::Representations::ProxyController#show`,
`ActiveStorage::Blobs::ProxyController#show`).

These entries look like: "Couldn't find template for digesting:
active_storage/representations/proxy/show".

These controllers use the method
`ActionController::ConditionalGet#http_cache_forever`,
and therefore `ActionController::ConditionalGet#combine_etags` method,
and therefore `ActionController::EtagWithTemplateDigest` module via
`etaggers` array.

`ActionController::EtagWithTemplateDigest` module requires a template
(view).

We have no views in ActiveStorage, so `EtagWithTemplateDigest` is
now turned off in ActiveStorage controllers by
`etag_with_template_digest` class attribute.

Records loaded from join queries are no longer automatically marked as
read-only since aff928ba.

Followup to 978421abd83d45b72e299f50a4fb324fcbdb3e00.

This reverts commit 05060ddb.

Tags are per-fiber, so they can't be cached in an instance variable.

Use segment instead of fragment in docs [ci-skip]

Refactor MemoryStore to use Hash ordering rather than key access times

Backward compatibility to work `Marshal.load(legacy_record.dump)` for MySQL

This is mainly to simplify the code and use less memory, as large hash can use quite a lot:

```ruby
>> ObjectSpace.memsize_of(1000.times.map { |i| [i, i]}.to_h)
=> 28768
>> ObjectSpace.memsize_of(10_000.times.map { |i| [i, i]}.to_h)
=> 458848
```

The performance is mostly not impacted, if not slightly better:

```ruby
require 'benchmark/ips'
require 'active_support/all'
@store = ActiveSupport::Cache::MemoryStore.new
@store.write("small", "small")
Benchmark.ips do |x|
  x.report("read:miss") { @store.read("miss") }
  x.report("read:small") { @store.read("small") }
  x.report("write:small") { @store.write("small", "small") }
end
```

6.0.3.2:
```
Warming up --------------------------------------
           read:miss    42.466k i/100ms
          read:small    25.315k i/100ms
         write:small    17.826k i/100ms
Calculating -------------------------------------
           read:miss    426.923k (± 1.9%) i/s -      2.166M in   5.074890s
          read:small    248.518k (± 2.7%) i/s -      1.266M in   5.097049s
         write:small    180.388k (± 1.6%) i/s -    909.126k in   5.041238s
```

This branch:
```
Warming up --------------------------------------
           read:miss    42.040k i/100ms
          read:small    28.364k i/100ms
         write:small    19.361k i/100ms
Calculating -------------------------------------
           read:miss    417.814k (± 2.1%) i/s -      2.102M in   5.033186s
          read:small    278.950k (± 2.8%) i/s -      1.418M in   5.088135s
         write:small    193.384k (± 1.8%) i/s -    968.050k in   5.007446s
```

Improve the docs for ordered options [ci skip]

Deduplicate some routing data

https://buildkite.com/rails/rails/builds/70443#aec9a148-b7b0-470c-92fb-977b4fccfb86/1020-1031

`attr_name` in `YAMLColumn` is not part of v1 YAML.

Ref #27773.

Context https://github.com/rails/rails/pull/39599#discussion_r445429365.

Similar with #39611.

Actually we never said we would keep Mashal compatibility between two
versions of Rails, so we sometimes directly removed the dedicated types
in the past (e.g. f1a0fa9e, #29666), but that direct removing makes cache
rotation harder.

Keeping the unused constant in new version at least during one version
will help cache rotation easier.

Remove redundant Exclude in .rubocop.yml

All `/tmp/` dirs are already excluded by line 11.

Speed up railties test test_skip_webpack_install currently ~10s

Use URI::DEFAULT_PARSER rather than instantiate a new one

Build running for doc pull request [ci skip]

Adding [ci skip] in commit message, does not prevent build from running.

The error being handled here was removed in
01c9782f.

Use LoadError#original_message if available in safe_constantize

Improve docs sentence structure [ci-skip]

Clarify what is not supposed to be in session in docs [ci-skip]

fix active storage cors configuration [ci skip]

Fix an error for `FileStore.cleanup` when using Sprockets