Change Special:ChangePassword to use OOUI
In order to work with OOUI properly, SpecialChangePassword::attemptReset() doesn't
throw PasswordErrors anymore. It now returns a Status object which
is set to fatal, if some requirement doesn't meet.
In OOUIHTMLForm: Handle Message objects as errors correctly. It's a valid parameter
for fatal to use a Message object instead of a message key, so OOUIHTMLForm needs
to handle Mesage objects as Message objects (can be parsed directly) instead of using
it as a message key (which usually doesn't exist).
Bug: T78373
Change-Id: Id768833bbd966cdeadd5a13fdb64b636ea2062ef