Deduplicate joins values

Added missing comment notation for the example of form_with in form_helpers.md documentation. [ci skip]

Prevent error on transliterate with frozen strings

Fix db:seed

Added missing changelog entry for new guide added for Multiple Databases with Active Record

[ci skip]

Added missing changelog entry for new guide added for Multiple Databases with Active Record(#36389) [ci skip]

To avoid a deprecation warning.

Preserve user supplied joins order as much as possible

To suppress the following warnings in tests.

```
~/rails/activerecord/lib/active_record/scoping/named.rb:190: warning: method redefined; discarding old not_sent
~/rails/activerecord/lib/active_record/scoping/named.rb:190: warning: previous definition of not_sent was here
```

[ci skip]

This was incorrectly added at 06401bb3.

Documentation for ActionMailer's SMTP over SSL/TLS option

[ci skip]

Remove redundant empty line when we don't use system test

Applications are not supposed to use require_dependency in their own
code if running in zeitwerk mode, and require_dependency was initially
aliased to require with that use case in mind.

However, there are situations in which you cannot control the mode and
need to be compatible with both. There, you might need require_dependency
in case you are being executed in classic mode. Think about engines that
want to support both modes in their parent applications, for example.

Furthermore, Rails itself loads helpers using require_dependency.

Therefore, we need better compatibility.

Fix typo in activerecord/CHANGELOG.md [ci skip].

Fix typo in activerecord CHANGELOG.md

[ci skip]

Allow separate database env variables per-connection

Update time_zone_options_for_select docs

Fix error 500 caused by ActionController::RoutingError (via fail-safe) when POST parameters are invalid (#29985)

* Reproduce error caused by malformed parameters

    Error:
    RequestFormat#test_format_does_not_throw_exceptions_when_invalid_POST_parameters:
    ActionDispatch::Http::Parameters::ParseError: 765: unexpected token at '{record:{content:24.12.1.146}}'
        /Users/weppos/Mirrors/rails/actionpack/lib/action_dispatch/http/parameters.rb:113:in `rescue in parse_formatted_parameters'
        /Users/weppos/Mirrors/rails/actionpack/lib/action_dispatch/http/parameters.rb:107:in `parse_formatted_parameters'
        /Users/weppos/Mirrors/rails/actionpack/lib/action_dispatch/http/request.rb:360:in `block in POST'
        /Users/weppos/.rvm/gems/ruby-2.3.3/gems/rack-2.0.3/lib/rack/request.rb:57:in `fetch'
        /Users/weppos/.rvm/gems/ruby-2.3.3/gems/rack-2.0.3/lib/rack/request.rb:57:in `fetch_header'
        /Users/weppos/Mirrors/rails/actionpack/lib/action_dispatch/http/request.rb:359:in `POST'
        /Users/weppos/Mirrors/rails/actionpack/lib/action_dispatch/http/parameters.rb:53:in `parameters'
        /Users/weppos/Mirrors/rails/actionpack/lib/action_dispatch/http/mime_negotiation.rb:62:in `block in formats'
        /Users/weppos/.rvm/gems/ruby-2.3.3/gems/rack-2.0.3/lib/rack/request.rb:57:in `fetch'
        /Users/weppos/.rvm/gems/ruby-2.3.3/gems/rack-2.0.3/lib/rack/request.rb:57:in `fetch_header'
        /Users/weppos/Mirrors/rails/actionpack/lib/action_dispatch/http/mime_negotiation.rb:60:in `formats'
        /Users/weppos/Mirrors/rails/actionpack/test/dispatch/request_test.rb:891:in `block in <class:RequestFormat>'

See GH-29983

* Capture parameter parsing error output and test it

This change prevents the log to be displayed in the tests.
Moreover, the assertion against the debug ensures that
the test effectively triggers the parsing error as expected.

* Use a generic value in the test

* Switch to assert_match

[Simone Carletti + Rafael Mendonça França]

Use a single term instead of all terms used to describe path and URL helpers together

Handle invalid string encodings and characters in ActiveSupport::Inflector.transliterate

Fix join middle table alias when using HABTM

Merge pull request #36764 from willianveiga/feature/inputs-inside-disabled-fieldset-are-not-submited-on-remote-true-forms

Inputs inside disabled fieldset are not submited on remote: true forms

Fix Bcc header missing with emails from conductor and test helpers

Removed webpacker:compile step from scaffold test as it is not required

Don't break configurations.each, .first before the deprecation period

[ci skip] add CSRF token explanation for javascript documentation

Add a default value for arg `format` in `ActionView::Digestor.digest()`

Update comment for ActionView::Digestor.digest [ci skip]

Fix flaky test ActionControllerBaseRenderTest#test_direct_render_to_string

Support :any variants for ActionView::FixtureResolver

Ability to test activejobs with relative delay

fix filenames of attachments created via the inbound email conductor

Add mention about `active_record.collection_cache_versioning` to the `new_framework_defaults.rb`

Only merge DATABASE_URL settings into the current env