* Remove the auth option checks as the auth plugins will validate
their own options
* Move the initialization of client_manager to the end of
initialize_app() so it is always called. Note that no attempts
to actually authenticate occur until the first use of one of the
client attributes in client_manager. This leaves
initialize_clientmanager() (formerly uathenticate_user()) empty
so remove it.
* Remove interact() as the client_manager has already been created
And there is nothing left.
* prepare_to_run_command() is reduced to trigger an authentication
attempt for the best_effort auth commands, currently the only
one is 'complete'.
* Add prompt_for_password() to ask the user to enter a password
when necessary. Passed to ClientManager in a new kward pw_func.
Bug: 1355838
Change-Id: I9fdec9144c4c84f65aed1cf91ce41fe1895089b2