Make `InactiveSessionThreshold` configurable in the web UI

[antonlyap]

Describe The Bug
When music playback is paused, it gets stopped after 10 minutes of inactivity.

Steps To Reproduce

1. Create a music library
2. Play any track and pause it
3. Wait 10 minutes
4. The playback is stopped

Expected Behavior
I would expect the player to stay paused and preserve the play queue indefinitely, like it does on the stable version.

System (please complete the following information):

• Platform: Docker, ARM64
• Browser: Firefox
• Jellyfin Version: latest unstable

Additional Context
There seems to be a Stop command coming from the server over WebSockets. Looking at the server code, it could be related to SyncPlay, which I'm not using.

Also, when I ran the unstable Jellyfin Docker image on x86, this issue didn't occur. I tried clearing the config and cache on the ARM machine, but to no effect.

[antonlyap]

So the culprit seems to be this PR: jellyfin/jellyfin#10357. Currently the functionality to stop inactive sessions doesn't seem to be documented anywhere and can only be configured by editing an XML file (/config/config/system.xml). Instances upgraded from stable (10.8.13) use the old configuration file and have the behavior disabled (that's why I didn't encounter it on the x86 system).

Would it be possible to make this option configurable via GUI?

[thornbill]

This is no longer enabled by default. Tagging this as a feature to add the setting to the ui.