Add some form of Steam Link integration

[mijofa]

Best bet is probably installing flatpak and com.valvesoftware.SteamLink.
But would also then need some level of Bluetooth support, and perhaps set up to autolaunch that app on Steam Controller connection

[mijofa]

First implemented in release jellyfin-media-player-2022-10-19-1666169304, but this has at least doubled the size of the SOE, and it's only really useful for my one frontend.
So I'd like to investigate an alternative.
Perhaps instead of installing the flatpak in the SOE itself I can just install Flatpak and set it's system data directory to /run/live/medium and allow for any generic flatpaks to be installed?

[mijofa]

Note, I should consider snapcraft over flathub and figure out which one I'd rather support, but SteamLink is only officially supported via flathub. I'm open to perhaps supporting both, but that sounds like more trouble than it's ever going to be worth.

[mijofa]

This has been greatly improved to be more generic for any number of other Flatpak apps (RetroArch is the main one I'd consider) but could still use some improvement.
Specifically with unmounting the flatpak filesystem when not in use, and the apps menu itself is kinda shit.