Draft: d3dx10: Add support for creating textures from DXGI_FORMAT_B4G4R4A4_UNORM DDS files.

Yakuza 6's Puyo Puyo minigame creates a texture from a DDS file that is the equivalent format of DXGI_FORMAT_B4G4R4A4_UNORM, which windowscodecs does not support.

This patch converts the texture into the equivalent of DXGI_FORMAT_R8G8B8A8_UNORM DDS file at the start of load_texture_data(), which allows us to avoid having an entirely separate code path for this specific image type. This current patch just handles the most basic of DDS files, if this approach seems reasonable I will flesh it out more, I just wanted to see if it was a good/bad idea before putting anymore work into it. :)