The purpose of MetaRenderDevice is to contain the logics related to a
render device; i.e. e.g. a gbm_device, or an EGLDevice. It's meant to
help abstract away unrelated details from where it's eventually used,
which will be by MetaRendererNative and the MetaOnscreenNative
instances.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1854>
