[git] refactor authenticator

* Handle Git plugin username/password storage in the same matter as for
  other auth providers, but make it the first provider to consider.
* Save the auth provider which was used for authentication (for future:
  to know where to remove the password from).
* Check auth providers in askPassword as well (before it was asked
  only in askUserName).

This is a preparation for IDEA-98189.
[git] IDEA-98189 Forget incorrect password

Github implementation is pending.
[git] Use GitImpl for all remote commands

Relates to IDEA-98189.
[git] remove an unused test class
[git] better error text
[git] IDEA-98189 Retry up to 3 times if authentication failed

But not if user explicitly cancelled the authentication dialog.
fix a copy paste misprint
[vcs] IDEA-67409 Support Home/End keys in the Log.
Test fixed (rt.jar on Apple JRE, again)
sometimes distraction free mode stays forever