Merge changes from topic "b129710438_2" into qt-dev

* changes:
  codec2: use media_codecs from apex and support variants/domains
  media: add media_codecs.xml to apex module
  media: expand media_codecs.xml to support variants and domains
  media/omx: Make OMX software plugin an actual plugin
  omx: only list existing OMX codecs in OmxStore