Reapply "vm-state: fix and improve testing"

This reverts commit 99092f6e76.

vm-state: revert sysusers, improve testing

zerotier: enable persistence

vm-state: cleanup tests

nixosModules/clanCore/state.nix

@@ -1,8 +1,9 @@
 { lib, ... }:
 {
   # defaults
-  # FIXME: currently broken, will be fixed soon
-  #config.clanCore.state.HOME.folders = [ "/home" ];
+  config.clanCore.state.HOME.folders = [
+    "/home"
+  ];
 
   # interface
   options.clanCore.state = lib.mkOption {