flake: inherit explicitly from parts of lib

Instead of doing `inherit (lib) <something>``, all inherits now use
`inherit (lib.<subsystem>) <something>`, which is much nicer.

modules/system/os/impermanence/module.nix

@@ -4,7 +4,7 @@
   lib,
   ...
 }: let
-  inherit (lib) mkIf mkForce;
+  inherit (lib.modules) mkIf mkForce;
   inherit (builtins) map;
 
   cfg = config.modules.system.impermanence;