Add Dolby Vision mkv support

I uploaded a sample Profile 5 Dolby Vision MKV file (from https://www.makemkv.com/download/dvtest/) that Infuse 6.5.2 on Apple TV 4K plays in SDR.

Video
ID                                       : 1
Format                                   : HEVC
Format/Info                              : High Efficiency Video Coding
Format profile                           : Main 10@L5.1@Main
HDR format                               : Dolby Vision, Version 1.0, dvhe.05.09, BL+RPU
Codec ID                                 : V_MPEGH/ISO/HEVC
Duration                                 : 56 s 200 ms
Bit rate                                 : 27.7 Mb/s
Width                                    : 3 840 pixels
Height                                   : 2 160 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 60.000 FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 10 bits
Bits/(Pixel*Frame)                       : 0.056
Stream size                              : 186 MiB (98%)
Language                                 : English
Default                                  : No
Forced                                   : No