Indeed, that complicates things. We could unify the installer logic between mods (at least RA and C&C, with D2K done after native-r8) but that is well outside the scope of this PR.

For now this would be best handled by attaching this (CncInstallMusicLogic) to the install button in music.yaml.

* `installButton` definition becomes `widget.Get<ButtonWidget>("INSTALL_BUTTON")`.
* `panel` can be removed along with the `NO_MUSIC_LABEL` (which should be in the music player logic for all mods).
*  `// TODO: MusicPlayerLogic` becomes `(MusicPlayerLogic)installButton.Parent.LogicObject`.