Unify source/header/entrypoint names Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/5457>
Compile HLSL at build time in case of MSVC, and use it if device supports shader model 5. Also cache/reuse pixel shader and vertex shader objects. Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/5426>