compositor-drm: Add universal plane awareness

Add awareness of, rather than support for, universal planes. Activate
the client cap when we start if possible, and if this is activated,
studiously ignore non-overlay planes. For now.

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 <lfrb@collabora.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>