compositor: add capability flag for arbitrary surface rotation

compositor: add capability flag for arbitrary surface rotation

The upcoming rpi-renderer cannot handle arbitrary rotations. Introduce
Weston capability bits, and add a bit for arbitrary rotation. GL and
Pixman renderers support it.

Shell or any other module must not produce surface transformations with
rotation, if the capability bit is not set. Do not register the surface
rotation binding in desktop shell, if arbitary rotation is not
supported.

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