Add support for NV12 to ``evr_render()``, as otherwise no video is rendered at all in games like Age of Empires II DE (see: https://github.com/ValveSoftware/Proton/issues/3189#issuecomment-1962984985)
Interestingly, this doesn't result in NV12 data being passed to ``evr_copy_sample_buffer()`` as I suspected, so the RGB32 copying code seems to work fine.
Nevertheless, add a warning if we get an unknown format in ``evr_copy_sample_buffer()``, as that could potentially lead to nasty memory issues (e.g., if we get the width/lines/stride wrong).
I confess, I don't really understand what's going on here: the format of the video is definitely ``MFVideoFormat_NV12`` in ``evr_render()``, but I never see any attempt to use NV12 in ``evr_copy_sample_buffer()`` — it's always ``MFVideoFormat_RGB32``. For that reason, I've also not tried to write any tests here — I don't know the MF API well enough to plumb this all the way through. On the bright side, though, the fact that everything mysteriously ends up as RGB32 means I haven't had to write an NV12 codepath for ``evr_copy_sample_buffer()`` — I'm not sure exactly how to handle the multi-plane formats there.
-- v3: evr/dshow: Support NV12 in evr_render