Add FFmpeg VVC decoder

Since FFmpeg 7.1, the VVC decoder is no longer marked as experimental.

During the execution of JVET-VVC_draft6, the FFmpeg VVC decoder got a
a score of 239/282 (84.75%).

fluster/decoders/ffmpeg.py

@@ -143,6 +143,7 @@ def check(self, verbose: bool) -> bool:
         codec_mapping = {
             Codec.H264: "h264",
             Codec.H265: "hevc",
+            Codec.H266: "vvc",
             Codec.VP8: "vp8",
             Codec.VP9: "vp9",
             Codec.AV1: "av1",
@@ -191,6 +192,13 @@ class FFmpegH265Decoder(FFmpegDecoder):
     codec = Codec.H265
 
 
+@register_decoder
+class FFmpegH266Decoder(FFmpegDecoder):
+    """FFmpeg SW decoder for H.265"""
+
+    codec = Codec.H266
+
+
 @register_decoder
 class FFmpegVP8Decoder(FFmpegDecoder):
     """FFmpeg SW decoder for VP8"""