Refactor: Initial step

- Added library for common functions
- Moved machines/ to hosts/
- Automise adding new hosts to the flake

hosts/workstation/persist.nix

@@ -0,0 +1,22 @@
+{ ... }:
+
+{
+  environment.persistence."/nix/persist" = {
+    hideMounts = true;
+    directories = [
+      "/var/log"
+      "/var/lib/nixos"
+      "/var/lib/systemd/coredump"
+      { 
+        directory = "/var/lib/colord";
+        user = "colord";
+        group = "colord";
+        mode = "u=rwx,g=rx,o=";
+      }
+    ];
+    files = [
+      "/etc/machine-id"
+    ];
+  };
+}
+