decodebin3: check and send selected stream message even if no decoder is selected
requested to merge elliot_chen/gstreamer:decodebin3-send-selected-stream-messsage-even-if-no-decoder-is-selected into main
- For some streams, maybe there is one track which can't select the right decoder while the other tracks can be decoded. Those streams will play error in gstreamer 1.24.7 version.
- To support such streams playback, need check and send selected stream message even if no decoder is selected in decodebin3.
Edited by elliot chen