ActionCable protocol negotiation

In particular, the fact that ApplicationController is the only
one inheriting from AC::API is not a default. You could say at
most that generators generate them that way, but the creation
of controllers is something which is out of our control because
programmers write controllers by hand.

Instead, we can say that normally, conventionally, as in the
majority of Rails apps, that is the actually the case.

This is primarily for backwards compatibility for when
or if the protocol is changed in future versions.

If the server fails to respond with an acceptable
protocol, the client disconnects and disables
the monitor.

Extend `ActionController::TestCase` deprecation warning

Update documentation based on the new changes for strong & weak ETags.

- Update info for weak ETag
- Add info for strong ETag
- Add examples for strong and weak ETags
- Display difference between generated strong and weak ETags strings.

Allow passing record being validated to error message generator

- Pass object to I18n helper so that when calling message proc, it will
  pass that object as argument to the proc and we can generate custom
  error messages based on current record being validated.
- Based on https://github.com/rails/rails/issues/856.

[Łukasz Bandzarewicz, Prathamesh Sonpatki]

Guides changes, follow up of #24401 [ci skip]

 [ci skip]

Fix marshal with autoloading for nested class/module

`number_to_phone` formats number with regexp

Use `QUOTED_TRUE` and `QUOTED_FALSE` instead of magic strings

Because we define `QUOTED_TRUE` as `"1"` and `QUOTED_FALSE` as `"0"`.
And add test cases to ensure this commit does not break current
behavior even if the value of `attributes_before_type_cast` is false.

[ci skip] Fix variable name

Fixes #24239

Added 'config.' to deprecation warning

  - skip calling helper_method if it's not there: if we don't have helpers, we needn't define one.
  - tests that an api controller can include and use ActionController::Cookies

enhance ActiveRecord#substitute_values to loop values just once

Previously `String#to_time` returned the midnight of the current date
in some cases where there was no relavant information in the string.
Now the method returns `nil` instead in those cases.

Fixes #22958.

The native DateTime#<=> implementation can be used to compare instances
with numeric values being considered as astronomical julian day numbers
so we should call that instead of returning nil.

Fixes #24228.

If the test run was interrupted in some way then it left temporary
directories inside of test causing the git worktree to be in a dirty
state. By overriding the run method we can use the block form of
Dir.mktmpdir to ensure that the directories are cleaned up no matter
which way the test run is exited.

The constant reference A::B used to trigger autoloading causes a warning
to be logged about the possible use of :: in a void context so assign it
to the _ variable to prevent the warnings from being triggered.

Update Rails 5.0 release notes

- Removed entry for # Template Collection from release notes.
- Remove duplicate entry for caching Action mailer views.
- Remove duplicate entry for left_outer_joins.

Grammar fixes based on pass over ETag doc changes

remove deprecated `datetime_field` from guide [ci skip]

`datetime_field` was deprecated in 316811b4

[ci skip]

Remove not needed including

By default, this method formats US number. This commit extends its
functionality to format number for other countries with a custom regular
expression.

    number_to_phone(18812345678, pattern: /(\d{3})(\d{4})(\d{4})/)
    # => 188-1234-5678

The output phone number is divided into three groups, so the regexp
should also match three groups of numbers.

Grammer fix in comment: capitalize first word in sentence [ci skip].

Because `DateTime` inherits `Date` and `Date` includes `DateAndTime::Zones`,
`DateTime` not need to include `DateAndTime::Zones` again.

Strong ETag validators

Fixes broken link in 'Ruby on Rails 2.2 Release Notes'