Start playing track when opened externally
When opening a file externally (ex. Dolphin), the user expects it to start playing immediately.
I fixed another bug where the metadata of the externally opened track wouldn't load correctly. So, BUG: 498357 ended up being fixed as a side effect.
Test plan
- Start playing any playlist on Elisa.
- Open one track externally.
- The track should be appended to the end of the playlist, or at random if the shuffle is enabled.
- The track will start playing immediately.