compositor-drm: Atomic modesetting support

compositor-drm: Atomic modesetting support

Add support for using the atomic-modesetting API to apply output state.
Unlike previous series, this commit does not unflip sprites_are_broken,
until further work has been done with assign_planes to make it reliable.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Co-authored-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Co-authored-by: Louis-Francis Ratté-Boulianne <louis-francis.ratte-boulianne@collabora.com>
Co-authored-by: Derek Foreman <derek.foreman@collabora.co.uk>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>