Add 2 tests, 1 of which fails, to isolate the digest_caching behaviour causing #12521

If config.action_view.cache_template_loading = false, most likely in a development
configuration if config.cache_classes = false &
config.action_controller.perform_caching = true.

config.action_view.cache_template_loading defaults to the value of config.cache_classes
Ensure ActionView::Digest.cache is correctly cleaned up when
ActionView::Resolver.caching = false.
update changelog
update digestor code based on review
[ci skip] Fix number of methods added by association.

Also clean up some trailing spaces on line 1143-1146.
add a new local variable to track if digests are being stored, to ensure the cleanup works correctly
Fix typo in form_helper.rb
Ensure the state is clean after one failure
Add Sass gobbling info to asset pipeline docs

[ci skip]
Make define_non_cyclic_method simpler
Fix some indentation on autosave association
Convert Fixnum into String the port number in MySQL
[ci skip] avoid deprecation warning in sample code

Account.find(1, lock: true)
-> DEPRECATION WARNING: Passing options to #find is deprecated. Please build a scope and then call #find on it.
In Relation#empty? use #exists? instead of #count.
Remove extra variable creation and merge.
Instrument the generation of Action Mailer messages

The processing of outbound mail is instrumented with the key
`process.action_mailer`. The payload includes the mailer name as well as
the mailer method.
Raise an exception when model without primary key calls .find_with_ids
Allow unscope to work with `where.not`

Allows you to call #unscope on a relation with negative equality operators,
i.e. Arel::Nodes::NotIn and Arel::Nodes::NotEqual that have been generated
through the use of where.not.
remove trailing whitespace added with b057765 [ci skip].
Fix loading a sql structure file on postgres when the file's path has whitespace in it