VAAPI: Add class which handles VPP deinterlacing
VAAPI: Integrate VPP into existing vaapi code
VAAPI, squash me: Add flush method to VPP class
VAAPI, squash me: Flush VPP
VAAPI, squash me: Don't fail permanently if one deint frame fails
VAAPI, squash me: Prefer Bob, as madi/mcdi doesn't work as reliable