Create a color manager type that eventually will be the high level
manager of color related behavior, such as ICC profiles and
color "temperature" a.k.a. night light.
For now, it's only an empty shell. It's also constructed by the actual
backend, as at a later point, the X11 and native color management
implementations will differ.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2141>
