Add libdisplay-info as a better alternative for parsing EDID. This way
we do not need to extend Weston's ad hoc parser for new things that
especially HDR support requires.

Eventually the ad hoc parser will be deleted and libdisplay-info becomes
a hard dependency for the drm-backend, reducing our maintenance burden.
Unlike the ad hoc code, libdisplay-info has automated CI testing.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>