Instead of our own implementation that upscales, then downscales back,
use graphene_matrix_inverse() directly. This is possible after switching
to a z-near value that doesn't have problems with float precision.
https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1489
Ideally, we would use Graphene to do that, however as of now Graphene
lacks these APIs so we still need these helpers. Since we're preparing
to get rid of CoglMatrix, move them to a separate file, and rename them
with the 'cogl_graphene' prefix.
Since I'm already touching the world with this change, I'm also renaming
cogl_matrix_transform_point() to cogl_graphene_matrix_project_point(),
as per XXX comment, to make it consistent with the transform/projection
semantics in place.
https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1439
