video: Add RGB10A2_LE pixel format
Packed 10 bits per each R, G and B channel with MSB 2bits alpha channel. This format is mapped to Windows' DXGI_FORMAT_R10G10B10A2_UNORM format which is required for 10bits HDR rendering.
Note that this RGB10A2_LE format is R - B channel swapped version of BGR10A2_LE