Reuse a result of `table.associated_table(column)` in `AssociationQueryHandler.value_for`

Currently `exists?` does some hackery where it assumes that we can join
onto anything that we passed to `eager_load` or `includes`, which
doesn't work if we are joining onto a polymorphic association.

Actually figuring out if we want to include something would require
knowledge deep within the join dependency module, which is hard to pull
up. The simplest solution is just to pass a flag down that says we're
not actually going to try to eager load any of the data. It's not the
solution I'd like, but that code really needs to be untangled before we
can do much with it.

This is another attempt at 6d5b1fdf which should address the concerns
that led to reverting it in 4ecabed2.

use OpenSSL::Cipher instead of deprecated OpenSSL::Cipher::Cipher

We now use default procs inside of the errors object, which gets
included by default when marshaling anything that includes
`ActiveModel::Validations`. This means that Active Record objects cannot
be marshalled. We strip and apply the default proc ourselves. This will
ensure the objects are YAML serializable as well, since YAML falls back
to marshal implementations now. This is less important, however, as the
errors aren't included when dumping Active Record objects.

This commit does not include a changelog entry, as 5.0 is still in RC
status at the time of writing, and 5.0.0 will not release with the bug
this fixes.

Fixes #25165

Fix migration class names in tests

Add a missing capital letter and avoid using absolute links to the
API because they may refer to out-dated documentation on the Edge
site.

Based on https://github.com/rails/rails/pull/25192#discussion_r65018222 and http://ruby-doc.org/stdlib-1.9.3/libdoc/openssl/rdoc/OpenSSL/Cipher/Cipher.html

Requesting documentation update

Change some establish_connection logic

Move new default initializers into separate directory

[ci skip]Fix wrong require path raising LoadError

ActionController::Parameters: Fix #dig doc code

This example code wasn't getting wrapped in a `<code>` tag due to incorrect indentation.

rename enum_prefix and enum_suffix options to _prefix and _suffix [ci skip]

`:enum_prefix` and `:enum_suffix` was changed to `:_prefix` and `:_suffix`
in #20999.

- These initializers are new defaults for Rails 5 and newly generated
  apps do not need to change them.
- Fixes #25181

Follow up to e45f388e.

When changing the generated integration tests to assert redirects with
an absolute path this redirection check in `assert_redirected_to` against
the absolute response location would now pass:
https://github.com/rails/rails/blob/af245aaf3a1c447752a1b5895adddc66e5f73c00/actionpack/lib/action_dispatch/testing/assertions/response.rb#L55

Thus we'd break early instead of hitting `assert_operator` and have
2 fewer assertions per `assert_redirected_to` as `assert_operator`
is composed of 2 assertions internally:
https://github.com/seattlerb/minitest/blob/4e146b1515b19a5c474e39c174b037510f6dbc6e/lib/minitest/assertions.rb#L254-L258

Deduct 2 assertions for 2 redirects taking the expected count down by 4
in total for the two failing tests.

Remove public/ files for API apps

The first comment does not explain anything that the code doesnt and the second is now irrelevant with the dedicated API mode

- Fixes #25180

fix incorrect class name [ci skip]

Use `add_index` instead of `execute` in guides [ci skip]

[ci skip] Reword doc for around_enqueue callback

Taken literally, the documentation suggests that the callback gets
called twice (before and after enqueueing). By wording it similarly to
that of around_perform this confusion is avoided.

cometic updates to security guide - fixes #25058 [ci skip]

Remove unused `association_for_table` private method

[ci skip] Fix ActionCable Guides

add missing `as` to request kwargs of `ActionDispatch::IntegrationTest`

Add test for `delegate_missing_to` where method doesn't exist

Follow up to #21671

Default worker pool size was changed from 100 to 4 at #24376