Try to bypass compositing if there is a fullscreen toplevel window with
a buffer compatible with the primary plane of the monitor it is
fullscreen on. Only non-mirrored is currently supported; as well as
fullscreened on a single monitor. It should be possible to extend with
more cases, but this starts small.
It does this by introducing a new MetaCompositor sub type
MetaCompositorNative specific to the native backend, which derives from
MetaCompositorServer, containing functionality only relevant for when
running on top of the native backend.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/798
