The ClutterBezier code was removed in
580d62b9b clutter: Remove unused Path related types
because it wasn't used anywhere. We do need a bezier curve for the
tablet tool pressure curve calculation though so let's move it
to the native backend and rename it to MetaBezier in the process.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3399>
