Adding d3d12 backend text renderer/blender by using d3d11on12 interop. And subclassing renderer object per backend (i.e., d3d11, d3d12, and bitmap) Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/6620>
... and simplify background rendering Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/5121>
For easy integration with a new text rendering baseclass Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/5121>