Fixes issue of metadata/lyrics not updating when switching tracks
The issue is due to TrackMetadataModel::trackData not providing
track data for tracks with Database ID of 0, which are tracks that
are missing title metadata and are not added into elisaDatabase.db.
In the fix, we remove the ID check. This introduces another issue,
where in ContextView.qml onDatabaseIdChanged would not update the
metadata/lyrics because the ID of tracks without metadata would be
0, and it wouldn't trigger the refresh of tracks changing. To alleviate
this, we'll instead monitor the filename of the track playing, and
when that changes, we update trackdata by the file URL.
On top of that, ContextView.qml onTrackTypeChanged now calls the proper function based on
whether the track has a database id or not.
We change the order of the notifying of database id and filename in manageheaderbar.cpp,
so we avoid the issue that the when the onFileUrlChanged is triggered, we actually have the
database id of the current track, instead of the previous. This allows us to use the correct function knowing whether the track is in the database or not. (Hope this doesn't break any behaviour elsewhere)
Also a fix for metadata not updating when opening files through Files-browser, this was caused by files being opened as ElisaUtils::FileName TrackType instead of ElisaUtils::Track. In the fix we just allow ModelDataLoader::loadDataByDatabaseIdAndUrl to handle filenames.