Fix unexpected select_tag delete behavior when include_blank is present

Need to new line to break line in the markdown.

* add leading `#` before `=>` since hash rocket is valid Ruby code
* add backticks
* remove trailing spaces
* and more

* Update RAILS_VERSION
* Bundle
* rake update_versions
* rake changelog:header

Revert "Remove finalizer and configuration"

This reverts commit 9e7b4a3173788ea43b11e74a4d2f69a5f1565daa.

https://github.com/rails/rails/blob/v6.0.0.beta1/actionview/CHANGELOG.md

[ci skip]

The `#csrf_meta_tags` and `#token_tag` Action View helper methods are
expecting the class in which are included to explicitly define the
method `#protect_against_forgery?` or else they will fail with
`NoMethodError`.

This is a problem if you want to use Action View outside of Rails
applications. For example, in #34788 I used the `#button_to` helper
inside of the error pages templates that have a custom
`ActionView::Base` subclass, which did not defined
`#protect_against_forgery?` and trying to call the button failed.

I had to dig inside of Action View to find-out what's was going on. I
think we should either set a default method implementation in the
helpers or check for the method definition, but don't explicitly require
the presence of `#protect_against_forgery?` in every `ActionViews::Base`
subclass as the errors are hard to figure out.

Generally followed the pattern for https://github.com/rails/rails/pull/32034

* Removes needless CI configs for 2.4
* Targets 2.5 in rubocop
* Updates existing CHANGELOG entries for fewer merge conflicts
* Removes Hash#slice extension as that's inlined on Ruby 2.5.
* Removes the need for send on define_method in MethodCallAssertions.

Firefox fires click events on left-, right-
and scroll-wheel (any non-primary mouse key) clicks while other browsers don't.

side of long lines; Fixes #34487

And remove trailing spaces.

This PR adds the allocations to the instrumentation for template and
partial rendering.

Before:

```
  Rendering posts/new.html.erb within layouts/application
  Rendered posts/_form.html.erb (9.7ms)
  Rendered posts/new.html.erb within layouts/application (10.9ms)
Completed 200 OK in 902ms (Views: 890.8ms | ActiveRecord: 0.8ms)
```

After:

```
  Rendering posts/new.html.erb within layouts/application
  Rendered posts/_form.html.erb (Duration: 7.1ms | Allocations: 6004)
  Rendered posts/new.html.erb within layouts/application (Duration: 8.3ms | Allocations: 6654)
Completed 200 OK in 858ms (Views: 848.4ms | ActiveRecord: 0.4ms | Allocations: 1539564)
```

The url_for method is now extracting the path_only option in order to determine if polymorphic_path or polymorphic_url should be called.

If the path_only option is not set it will be set to true unless the host option is set. This behaviour is the same as when a Hash or Params object is passed.

To support this unifying the code responsible for setting this default value has been extracted into a private method

Fixing code block rendering, indentation, backticks, etc.

Instead of dropping it completely in case someone is relying (probably
inadvertenly) on it.

Avoid exposing private methods in view's helpers.

Fixes https://github.com/rails/rails/issues/33546

`button_to` was throwing exception when invoked with `params` hash that
contains symbol and string keys. The reason for the exception was that
`to_form_params` was comparing the given symbol and string keys.

The issue is fixed by turning all keys to strings inside
`to_form_params` before comparing them.

names. Lambda should be passed to use this option. Example:

    date_select('user_birthday', '', start_year: 1998, end_year: 2000, year_format: ->year { "Heisei #{year - 1988}" })

The HTML produced:

    <select id="user_birthday__1i" name="user_birthday[(1i)]">
    <option value="1998">Heisei 10</option>
    <option value="1999">Heisei 11</option>
    <option value="2000">Heisei 12</option>
    </select>
    /* The rest is omitted */

As of now,  `HTMLElement.nonce` seems to work only in Chrome.
So, it should not be used now.
https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/nonce#Browser_compatibility

Fixes #32577.

- Add missing dots at the end of sentences.
- Wrap RecordTagHelper into `.
- `RecordTagHelper` => `ActionView::Helpers::RecordTagHelper`.

[ci skip]

* Since #18411, we started to inform about extracted gem (record_tag_helper)
  to developers who use `ActionView::Helpers::RecordTagHelper` 's methods.

* Currently, it seems no problem that we don't have to support no longer.

ActionView::Template instances compile their source to methods on the
ActionView::CompiledTemplates module. To prevent leaks in development
mode, where templates can frequently change, a finalizer is added that
undefines these methods[1] when the templates are garbage-collected.

This is undesirable in the test environment, however, as templates don't
change during the life of the test. Moreover, the cost of undefining a
method is proportional to the number of descendants a class or module
has, since the method cache must be cleared for all descendant classes.

As ActionView::CompiledTemplates is mixed into every
ActionView::TestCase (or in RSpec suites, every view spec example
group), it can end up with a very large number of descendants, and
undefining its methods can become very expensive.

In large test suites, this results in a long delay at the end of the
test suite as all template finalizers are run, only for the process to
then exit.

To avoid this unnecessary cost, this change adds a config option,
`action_view.finalize_compiled_template_methods`, defaulting to true,
and sets it to false in the test environment only.

[1] https://github.com/rails/rails/blob/09b2348f7fc8d4e7191e70e06608c5909067e2aa/actionview/lib/action_view/template.rb#L118-L126