qtdemux: parse stream tags
qtdemux: parse stream tags

Keep global and stream tags separately and parse the udta node
that can be found under the trak atom. The udta will contain
stream specific tags and will be pushed as such

https://bugzilla.gnome.org/show_bug.cgi?id=692473

sebras/gst-plugins-good,ijsf/OpenWebRTC-gst-plugins-good,Kurento/gst-plugins-good,freedesktop-unofficial-mirror/gstreamer__gst-plugins-good,chamois94/gst-plugins-good,ijsf/OpenWebRTC-gst-plugins-good,ijsf/OpenWebRTC-gst-plugins-good,froggatt/gst-plugins-good-m,pexip/gst-plugins-good,sebras/gst-plugins-good,shelsonjava/gst-plugins-good,hizukiayaka/gst-plugins-good,loshca/gst-plugins-good,GrokImageCompression/gst-plugins-good,sh0/gst-plugins-good,vatavuserban/gst-plugins-good,ikonst/gst-plugins-good,GrokImageCompression/gst-plugins-good,Kurento/gst-plugins-good,kittee/gst-plugins-good,shelsonjava/gst-plugins-good,stfl/gst-plugins-good,rawoul/gst-plugins-good,chamois94/gst-plugins-good,loshca/gst-plugins-good,sh0/gst-plugins-good,ikonst/gst-plugins-good,veo-labs/gst-plugins-good,stfl/gst-plugins-good,Kurento/gst-plugins-good,GStreamer/gst-plugins-good,BigBrother-International/gst-plugins-good,GStreamer/gst-plugins-good,kittee/gst-plugins-good,GrokImageCompression/gst-plugins-good,shelsonjava/gst-plugins-good,sh0/gst-plugins-good,pexip/gst-plugins-good,ijsf/OpenWebRTC-gst-plugins-good,GStreamer/gst-plugins-good,veo-labs/gst-plugins-good,vatavuserban/gst-plugins-good,freedesktop-unofficial-mirror/gstreamer__gst-plugins-good,sebras/gst-plugins-good,StreamUtils/gst-plugins-good,StreamUtils/gst-plugins-good,pexip/gst-plugins-good,loshca/gst-plugins-good,BigBrother-International/gst-plugins-good,freedesktop-unofficial-mirror/gstreamer__gst-plugins-good,Kurento/gst-plugins-good,BigBrother-International/gst-plugins-good,chamois94/gst-plugins-good,chamois94/gst-plugins-good,ikonst/gst-plugins-good,GStreamer/gst-plugins-good,loshca/gst-plugins-good,StreamUtils/gst-plugins-good,stfl/gst-plugins-good,pexip/gst-plugins-good,froggatt/gst-plugins-good-m,rawoul/gst-plugins-good,hizukiayaka/gst-plugins-good,vatavuserban/gst-plugins-good,veo-labs/gst-plugins-good,froggatt/gst-plugins-good-m,GrokImageCompression/gst-plugins-good,ikonst/gst-plugins-good,veo-labs/gst-plugins-good,StreamUtils/gst-plugins-good,kittee/gst-plugins-good,BigBrother-International/gst-plugins-good,sh0/gst-plugins-good,rawoul/gst-plugins-good,shelsonjava/gst-plugins-good,hizukiayaka/gst-plugins-good,Kurento/gst-plugins-good,froggatt/gst-plugins-good-m,hizukiayaka/gst-plugins-good,pexip/gst-plugins-good,sebras/gst-plugins-good,rawoul/gst-plugins-good,stfl/gst-plugins-good,vatavuserban/gst-plugins-good,freedesktop-unofficial-mirror/gstreamer__gst-plugins-good,kittee/gst-plugins-good