Hard-deprecate password handling in User

Hard-deprecate password handling in User

Add wfDeprecated for User::checkPassword(), User::setPassword(),
User::setInternalPassword() and User::checkTemporaryPassword().
With AuthManager mediating between the caller and a set of
authentication providers in a potentially multi-step process,
a password check or change now cannot always be expressed
with a single-step succed-or-fail process. Callers should use
AuthManager::beginAuthentication() with a PasswordAuthenticationRequest
for password checks, and AuthManager::changeAuthenticationData()
for a password change.

Bug: T91699
Change-Id: Ib0ae8f1ff10ae6c2655d529db8b3a32e0cb489b0