Use uresourced

Summary

• Package and use this: https://gitlab.freedesktop.org/benzea/uresourced
• Revert (partially?) b3511492
• Make sure cgroupify works with Flatpaks and fix it if not

Reasoning

This project installs some workarounds to make session management (esp. w/ oomd) a bit better. Part of what it does is splitting individual browser tabs into their own cgroups (so they get killed individually rather than the whole browser all at once).

Also does some resource allocation to active graphical users. Perhaps could supplant and/or supplement #68?

We should revert the above mentioned commit because it made oomd too tame (now oomd fails to free memory before the system freezes). Perhaps this here is a better solution.

Prior Art

Fedora has shipped this since F33: https://fedoraproject.org/wiki/Changes/Reserve_resources_for_active_user_WS