[ticket/9388] Only display the settings for the selected method in the auth and search ACP pages.

This also switches the avatar type toggles to use the new toggle method and in the process fixes the subsilver2  toggle. It wasn't working due to a syntax error:
```Error: Syntax error, unrecognized expression: .[class^="avatar_option_"]```

https://tracker.phpbb.com/browse/PHPBB3-9388