* Better comments
* Reorganize code so related settings are close to each other
* Add ::1 to the "localhost" patterns we look for
* Make the dest_port parameter override the ansible_ssh_port setting
* Fix dest_port (wasn't being set)
* more complete detection of delegate_to
* Fix set_remote_user (wasn't being looked for in parameters)
* Instead of removing mode here, have the ansible module accept it
(better documents the parameters doing it htat way)
Also making PlayContext a child class of the Playbook Base class,
which gives it access to all of the FieldAttribute code to ensure
field values are correctly typed after post_validation
Fixes#11381