direct3d11 shaders are not mapping subpicture to HDR

With an HDR video output, subpictures are overlayed as SDR, which result in subtitles/subpictures being black with HDR10.

Either we should have a shader cache for subpicture, but compilation of the shader might drop a frame, or we should use a generic shader for subpicture to do the sampling and the mapping to same format as the video.

See also https://forum.videolan.org/viewtopic.php?f=14&t=149863&p=492772#p492772

See also #24891 (closed)

mentioned in issue #24891 (closed)

marked this issue as related to #18088

marked this issue as related to #24891 (closed)

changed the description

added Component::Video: Direct3D / Win32 label