DESKPROFILE: Introduce the new IPA session provider
    
    In order to provide FleetCommander[0] integration, a session provider
    has been introduced for IPA. The design of this feature and more
    technical details can be found at [1] and [2], which are the design
    pages of both freeIPA and SSSD parts.
    
    As there's no way to test freeIPA integration with our upstream tests,
    no test has been provided yet.
    
    Is also worth to mention that the name "deskprofile" has been chosen
    instead of "fleetcmd" in order to match with the freeIPA plugin. It
    means that, for consistence, all source files, directories created,
    options added, functions prefixes and so on are following the choice
    accordingly.
    
    [0]: https://wiki.gnome.org/Projects/FleetCommander
    [1]: https://github.com/abbra/freeipa-desktop-profile/blob/master/plugin/Feature.mediawiki
    [2]: https://docs.pagure.org/SSSD.sssd/design_pages/fleet_commander_integration.html
    
    Resolves:
    https://pagure.io/SSSD/sssd/issue/2995
    
    Signed-off-by: Fabiano Fidêncio <fidencio@redhat.com>
    
    Reviewed-by: Pavel Březina <pbrezina@redhat.com>
    Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>