use soteria instead of kde-polkit-agent as its a lot faster

[zimward]

Rational: currently the niri-flake-polkit is very slow to respond (multiple seconds usually). you also mentioned that you eventually want to retire the unit completely, which is sane.
Soteria is maintained by upstream nixpkgs and switching to it should not cause any breakage (apart from maybe some window rules).

[sodiboo]

hi, this is a good change. i agree. soteria is way better. people should probably be using that.

however, i also want to like, deprecate the module i have for installing niri on NixOS? it's mostly redundant with nixpkgs. both of them install niri, and as is evident, my module simply does that part slightly worse than upstream.

people should be using soteria but they should also be using the nixpkgs module to install niri.

i'm currently working on cleaning up a bunch of tech debt, in which i plan to actually deprecate/remove that module and replace it with instructions on what to do instead (notably, "what to do instead" is stuff that currently, on the main branch, is not very usable).

as such, i don't really want to merge this and change the behaviour of that module right before it's gone? but until that mostly-cleanup work is done, i won't close this PR. because like, it hasn't been superseded yet.