Use the config value directly when call `secrets`

Currently, `read_encrypted_secrets` is set with initializer.
Therefore if refer to `secrets` in config, `read_encrypted_secrets` is false,
so can not get the value of `secrets.yml.enc`.

In order to be able to refer to secrets in config, modified to refer to
`config.read_encrypted_secrets` when calling `secrets`.

Fixes #28618.

Changelog links at the top of the components, and lowercased the 'c' in
notable changes. Personally, the styling isn't super important to me, but
it's what we always done in previous guides, so I figured it's better to
keep with what we've always done.

[ci skip]

Prevent aliases Array#append and Array#prepend

Started adding release notes for Rails 5.1 [ci skip]

Rename `association_query_handler.rb` to `association_query_value.rb`

Early return in `PredicateBuilder::ArrayHandler`

Partitioning to `values` and `nils` is unneeded before early return.

Since `AssociationQueryHandler` and `PolymorphicArrayHandler` has
removed in #28715, only exists `AssociationQueryValue` and
`PolymorphicArrayValue` in these files.

Fix module name [ci skip]

Replace `FormOptionHelper` to `FormOptionsHelper`.

Move around AR::Dirty and fix _attribute method

We already have a _read_attribute method that can get the value we need
from the model.  Lets define that method in AM::Dirty and use the
existing one from AR::Dirty rather than introducing a new method.

Fix inconsistency with changed attributes when overriding AR attribute reader

Support `:offset` in `Time#change` and `:zone` or `:offset`
in `ActiveSupport::TimeWithZone#change`.

Fixes #28723.

Convert association queries to PORO queries

Add a test case for #20802

Fix mistake in JS response parser

Make code statistics task handle system tests properly

Close form_for tag in FormHelper API docs

  -
  Restore ability to accept ecmascript
  JS response should not modify DOM.

If it is not added to `TEST_TYPES`, it is not regarded as a test
when counting the total count.

The issue #20802 has been fixed in cc0b566a.

Closes #20802.

[ci skip]

Add comprehensive locking around DB transactions

Tweaks #28678

Use a query that's compatible with PostgreSQL 9.2

Also, explicitly apply the order: generate_subscripts is unlikely to
start returning values out of order, but we should still be clear about
what we want.

Was looking through #28402, and realized the CHANGELOG.md entry is in the wrong
place. Sorry we didn't catch this during code review 😢

[ci skip]

[ci skip]

Fix rubocop violations

Add `action_controller_base` and `action_controller_api` hooks to mitigate differences between them. Also document Active Support on_load hooks

Don't freeze input strings

rails-ujs: missing default url for ajax requests.

See 34321e4a for background on
ImmutableString vs String.

Our String type cannot delegate typecasting to ImmutableString, because
the latter freezes its input: duplicating the value after that gives us
an unfrozen result, but still mutates the originally passed object.

Update routing doc on the `get` `to:` option [ci skip]