Update to .NET 9

See merge request !58

Also update all NuGet packages

Project locking and auth redirects

See merge request !57

Fix auth in ArtifactDetailEndpoint

See merge request !56

Allow moving of project groups and playlists between organizations and make improvements to the UI

See merge request !55

In that case the current user needs to have write perms to both the old and the new organization.

Organizations features and UI

Closes #173

See merge request !54

This actually makes sense since we have the legacy org and potentially some other ones we might want to hide.