compositor: add icc_profile weston.ini option for outputs

This adds "icc_profile" key support in [output] sections for backends
headless, x11, wayland, and drm, and also for remoted and pipewire
outputs FWIW. On the other hand, RDP-backend does not use output
sections from weston.ini, and fbdev-backend does not deserve anything
new (it wouldn't support color management anyway due to no GL-renderer).

This allows one to configure an ICC v2 or v4 file to be used as an
output profile. However, color-lcms does not actually use output
profiles yet, so trying this will fail until support is implemented.

The parent_winsys_profile argument is reserved for using the color
profile from a parent window system where applicable, if nothing else is
set in weston.ini. None of the nested backends provide an output color
profile yet. It is more of a reminder of a missing feature than a
serious implementation.

Note: cms-static Weston plugin uses the exact same weston.ini key for
loading VCGT from ICC profiles. If "color-management" option is set to
false, this new use of "icc_profile" is disabled and the old behavior
with cms-static is kept.

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