Support 10-bit YUV in color converter for thumbnails

Handle 10-bit source YUV in convertYUV420Planar(), drop to
to 8-bit and convert to RGB.

Also drop to 8-bit in SoftwareRenderer if the dataspace is
not BT2020 and PQ, in this case surfaceflinger will not
treat the buffer as Y410 and we have to send in YV12.

Bug:77892138

Test:
- Temporarily disable USE_LIBYUV in ColorConverter (force
  convertYUV420Planar), test HEIF decoding to ARGB/RGB565 works
- Disable HW VP9 decoding in media_codecs.xml, push test clip
  in bug and check playback as well as thumbnail in Photos.
- Check VP9 HDR playback in ExoPlayer with SoftVPX path enabled.

Change-Id: I8fd2a34c9d52a9a5b1160f42b7a6226d5c5f608c