avcodec/internal: add FFCodec.color_ranges

I went through all codecs and put them into five basic categories:

1. JPEG range only
2. MPEG range only
3. Explicitly tagged
4. Broken (codec supports both but encoder ignores tags)
5. N/A (headerless or pseudo-formats)

Filters in category 5 remain untouched. The rest gain an explicit
assignment of their supported color ranges, with codecs in category
4 being set to MPEG-only for safety.

It might be considered redundant to distinguish between 0 (category 5)
and MPEG+JPEG (category 3), but in doing so we effectively communicate
that we can guarantee that these tags will be encoded, which is distinct
from the situation where there are some codecs that simply don't have
tagging or implied semantics (e.g. rawvideo).

A full list of codecs follows:

JPEG range only:
 - amv
 - roqvideo

MPEG range only:
 - asv1, asv2
 - avui
 - cfhd
 - cljr
 - dnxhd
 - dvvideo
 - ffv1
 - flv
 - h261, h263, h263p
 - {h263,vp8}_v4l2m2m
 - huffyuv, ffvhuff
 - jpeg2000
 - libopenjpeg
 - libtheora
 - libwebp, libwebp_anim
 - libx262
 - libxavs, libxavs2
 - libxvid
 - mpeg1video, mpeg2video
 - mpeg2_qsv
 - mpeg2_vaapi
 - mpeg4, msmpeg4, msmpeg4v2, wmv1, wmv2
 - mpeg4_omx
 - prores, prores_aw, prores_ks
 - rv10, rv20
 - snow
 - speedhq
 - svq1
 - tiff
 - utvideo

Explicitly tagged (MPEG/JPEG):
 - {av1,h264,hevc}_nvenc
 - {av1,h264,hevc}_vaapi
 - {av1,h264,hevc,vp8,vp9,mpeg4}_mediacodec
 - {av1,h264,hevc,vp9}_qsv
 - h264_amf
 - {h264,hevc,prores}_videotoolbox
 - libaom-av1
 - libkvazaar
 - libopenh264
 - librav1e
 - libsvtav1
 - libvpx, libvpx-vp9
 - libx264
 - libx265
 - ljpeg
 - mjpeg
 - vc2

Broken (encoder ignores tags):
 - {av1,hevc}_amf
 - {h264,hevc,mpeg4}_v4l2m2m
 - h264_omx
 - libxeve
 - magicyuv
 - {vp8,vp9,mjpeg}_vaapi

N/A:
 - ayuv, yuv4, y41p, v308, v210, v410, v408 (headerless)
 - pgmyuv (headerless)
 - rawvideo, bitpacked (headerless)
 - vnull, wrapped_avframe (pseudocodecs)

libavcodec/vaapi_encode_vp8.c

@@ -264,6 +264,7 @@ const FFCodec ff_vp8_vaapi_encoder = {
         AV_PIX_FMT_VAAPI,
         AV_PIX_FMT_NONE,
     },
+    .color_ranges   = AVCOL_RANGE_MPEG, /* FIXME: implement tagging */
     .hw_configs     = ff_vaapi_encode_hw_configs,
     .p.wrapper_name = "vaapi",
 };