WebUI: Add support for login for AD users
    
    After login, method user-find --whoami was called which cannot be
    called for AD users. That method was replaced by ipa whoami command
    and sequential command according to result of ipa whoami. AD user
    can now be logged in.
    
    AD users have new menu definition which contains only list of IPA
    users and profile page of AD user - "User ID Override".
    
    This commit also fixes several places where IPA.whoami object was
    used, because its structure was also changed. It now contains two
    objects. First one is stored in 'metadata' property and stores
    result from ipa whoami (type of object, command which should be
    called for showing detailed data about currently logged entity, etc).
    The second one is stored in 'data' property which stores result of
    _show command for currently logged entity.
    
    https://pagure.io/freeipa/issue/3242
    
    Reviewed-By: Petr Vobornik <pvoborni@redhat.com>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>