Deprecated code followup: rework controller, add 2 new tests

Problem/Motivation

After the initial port and followup some issues still needed work. Changes in this patch bring the code more in line with core and will improve comments and test coverage for the controller.

Changes:

1. MessengerInterface $messenger param is dropped from confirmAccount() and LoggerInterface $logger replaces it.
2. $logger is now used to log the notice
3. messages set changed - error/status/warning/message on pages where core renders error/status/warning/message messages
4. 2 new tests, 1 to complete the controller cases, 1 to just make sure deleted users can't use a confirmation url.
5. $route_name and $route_options vars are dropped from the controller.

Remaining tasks

Review, commit.