[Task Manager] Show MPRIS Raise only for launchers
Previously, it was implied that "Launch new instance" is only shown for windows but this has changed, leading to a "Restore" entry that doesn't really make sense for windows.
The idea is that, if there is no window associated with the player (e.g. pinned to task manager and playing without window) you can then get the player window back through MPRIS.
- I no longer get an awkward "Restore" item on all my browser windows
- I still get it for a pinned Cantata playing in the background without a window