Update Getting Started guide to reflect foreign key in migration [ci skip]

 ActiveJob is not ActionJob [ci skip] 😄

Raise a better exception for renaming long indexes for mysql adapters

ActiveJob testing improvements

This error only happens when the foreign key is missing.

Before this fix the following exception was being raised:

    NoMethodError: undefined method `val' for #<Arel::Nodes::BindParam:0x007fc64d19c218>

Now the message is:

    ActiveRecord::UnknownAttributeError: unknown attribute 'foreign_key' for Model.

ActiveJob: delegate deserialization to the job class

encapsulate env in the request so that we can eventually move away from
the env hash

this will help decouple us from using the rack env hash

Load a has_one target for a new record if possible

Flatten the call stacks ActiveSupport::Callbacks produces, fix #18011.

PostgreSQL, Fix change detection caused by superfluous bytea unescaping

Fixes simple missprint in docs for #cyle in text_helper [ci skip]

Fix comment typo in debugger.rb [ci skip]

RoutingAssertions. [ci skip]

after views. [ci skip]

 Update CHANGELOG entry for #18070 [ci skip]

functional testing section and implement :show, :destroy, and :update tests.

[ci skip]

 - Improved wording of CHANGELOG entry for https://github.com/arthurnn/rails/commit/5acd24bbeae0e9e5e81e87b5929e17f35527b2ea.

Ensures that primary_key method will return nil when multi-pk

in the Action Dispatch Integration module. [ci skip]

When table has a composite primary key, the `primary_key` method for
sqlite3 and postgresql was only returning the first field of the key.

Ensures that it will return nil instead, as AR dont support composite pks.

Use more semantic method to authenticate password in SecurePassword

 Fix description for application_name method - change simple to simply [ci skip]

 [ci skip]