lavf/mxfdec: add j2k to intra only codecs
lavf/mxfdec: generate ptses for interlaced j2k streams

Ptses are generated so that the two packets required for a given
frame would have the same pts. This hack prevent frame duplication
in ffmpeg.

pkt0.pts = 0, pkt1.pts = 0 -> decoded_frames.pkt_pts = 0
pkt2.pts = 1, pkt3.pts = 1 -> decoded_frames.pkt_pts = 1
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