compositor-drm: Support plane IN_FORMATS

The per-plane IN_FORMATS KMS property describes the format/modifier
combinations supported for display on this plane. Read and parse this
format, storing the data in each plane, so we can know which
combinations might work, and which combinations definitely will not
work.

Similarly to f11ec02c ("compositor-drm: Extract overlay FB import to
helper"), we now use this when considering promoting a view to overlay
planes. If the framebuffer's modifier is definitely not supported by the
plane, we do not attempt to use that plane for that view.

This will also be used in a follow-patch, passing the list of modifiers
to GBM surface allocation to allow it to allocate more optimal buffers.

Signed-off-by: Sergi Granell <xerpi.g.12@gmail.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Tested-by: Emre Ucan <eucan@de.adit-jv.com>