Set to `form_with_generates_remote_forms` only when config is explicitly specified

Without this check, even if config is not specified, `ActionView::Helpers::FormHelper.form_with_generates_remote_forms`
always be set to nil and remote form not be generated.

Follow up to 128b804c

This is a small breaking change that we chose to make in 5.1 since the
fix can be done with a search and replace tool.

This configuration is not present in ActionView::Base so we can't let
the action_view.set_configs initializer set it.

Also add tests to make sure this config works.

Fixes #28824

Update 'Building Complex Forms' with `inverse_of`

Add missing require

Fix #24032

Fixes #24032

Prevent double firing the before save callback of new object when the parent association saved in the callback

Without this, unit test fails.

```
bundle exec ruby -w -Ilib:lib:test test/cases/logging_test.rb
Using inline
Run options: --seed 41246

# Running:

SE......S....

Finished in 0.052938s, 245.5696 runs/s, 831.1585 assertions/s.

  1) Error:
LoggingTest#test_job_error_logging:
NameError: uninitialized constant LoggingTest::RescueJob
    test/cases/logging_test.rb:130:in `rescue in test_job_error_logging'
    test/cases/logging_test.rb:129:in `test_job_error_logging'

13 runs, 44 assertions, 0 failures, 1 errors, 2 skips

You have skipped tests. Run with --verbose for details.
```

[ci skip]

Prevent double firing the before save callback of new object when the parent association saved in the callback

Related #18155, #26661, 268a5bb0, #27434, #27442, and #28599.

Originally #18155 was introduced for preventing double insertion caused
by the after save callback. But it was caused the before save issue
(#26661). 268a5bb0 fixed #26661, but it was caused the performance
regression (#27434). #27442 added new record to `target` before calling
callbacks for fixing #27434. But it was caused double firing before save
callback (#28599). We cannot add new object to `target` before saving
the object.

This is improving #18155 to only track callbacks after `save`.

Fixes #28599.

Fix quoting in db:create grant all statement.

Add error logging to Active Job

Fixes Hash.from_xml with frozen strings for all engines

Namespace CSS selectors on error pages

The css selectors on the generated error pages are too broad (for example `text-align: center` on `body` and thus bleed out to the following pages (say, by pressing the back button) when using Turbolinks. This commit namespaces all the selectors.

Remove outdated comment

The database name used in the test would have actually shown this if it
had tried to execute on a real Mysql instead of being stubbed out
(dashes in database names needs quotes).

Since 3aee9126, this class hasn't inherited from Array.

Don't fallback to utf8mb3 after MySQL 8.0.0

`cache_key` respects the limit in a relation even if a relation is not loaded

Don't generate system test files if `skip_system_test` option is specified

Closes #28382
Closes #28651

Log any write errors originating from the socket

Fix migration tasks

Include gem name and deprecation horizon when calling the deprecation behaviors

Send deprecation horizon and gem name as arguments to deprecation heavier handler, and make sure they are used for the ActiveSupport::Notifications message.

Improve the upgrade path of Strong Parameters

Raise error on the movement of migrations
when the current migration does not exist.

Sentence had some awkward grammar and was kind of confusing, tried to make it easier
to understand what it was trying to say :)

[ci skip]

[ci skip] Changed plain text to NOTE.

Use `quoted_scope` rather than `@config[:database]` to respect current database