#208
Process is this:
Add source tag as "youtube" to all existing nfo's, this is because there is no way accurately track previous downloaded files....
Then any youtube sourced file will be upgraded if a "tidal" sourced file is available that has the same file name. This does result in all previous "tidal" files being re-downloaded, but much better than all files being downloaded...
Per discussion on #141, this PR adds the ability to specify a videoDownloadTag.
If a value is specified for videoDownloadTag, only artists tagged in Lidarr with
the specified tag will have videos downloaded for them. If videoDownloadTag is
left empty (the default), things work exactly as they did prior to introducing
this feature.