gst/mxf/: Add the codec name, and if possible the avg bitrate, to the pad's taglist.

gst/mxf/: Add the codec name, and if possible the avg bitrate, to the pad's taglist.

Original commit message from CVS:
* gst/mxf/mxfaes-bwf.c: (mxf_bwf_create_caps):
* gst/mxf/mxfalaw.c: (mxf_alaw_create_caps):
* gst/mxf/mxfdemux.c:
(gst_mxf_demux_handle_generic_container_essence_element):
* gst/mxf/mxfdv-dif.c: (mxf_dv_dif_create_caps):
* gst/mxf/mxfjpeg2000.c: (mxf_jpeg2000_create_caps):
* gst/mxf/mxfmpeg.c: (mxf_mpeg_es_create_caps),
(mxf_mpeg_create_caps):
Add the codec name, and if possible the avg bitrate, to the pad's taglist.