vout: remove direct3d9 display module

Since we require Windows 7 with D3D11. We can always use D3D11 there. We don't need an inferior (no HDR, no 360) variant.

We support D3D11 to the lowest level of D3D9 driver compatibility.

DXVA2 decoder and D3D9 video filters are kept as it's the only way to have hardware decoding with OpenGL for now.

Draft on top of !5859 (merged) as it needs to be kept if we allow supporting Win7 without D3D11. Draft on top of !5905 (merged) which adds equivalent hardware decoding support even with old GPUs/drivers.