This commit consolidates DRM buffer management to the MetaDrmBuffer
types, where the base type handles the common functionality (such as
managing the framebuffer id using drmModeAdd*/RMFb()), and the sub types
their corresponding type specific behavior.
This means that drmModeAdd*/RmFB() handling is moved from meta-gpu-kms.c
to meta-drm-buffer.c; dumb buffer allocation/management from
meta-renderer-native.c.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1488>
There is no reason why we should have an internal type enum when we have
all the infrastructure to just use multiple GObject types. Also there
was no code sharing between the old "types", the only common API was
getting the framebuffer ID, so lets make that a vfunc.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/584
