refactor(users/tazjin): Extract non-home persistence config

This will be reused between machines.

Change-Id: Ice7835ce7e63b00284e046606309e882412cda26
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5547
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: tazjin <tazjin@tvl.su>

users/tazjin/nixos/modules/persistence.nix

@@ -0,0 +1,24 @@
+# Configuration for persistent (non-home) data.
+{ depot, pkgs, lib, ... }:
+
+{
+  imports = [
+    "${depot.third_party.impermanence}/nixos.nix"
+  ];
+
+  environment.persistence."/persist" = {
+    directories = [
+      "/etc/NetworkManager/system-connections"
+      "/etc/mullvad-vpn"
+      "/var/cache/mullvad-vpn"
+      "/var/lib/bluetooth"
+      "/var/lib/systemd/coredump"
+      "/var/lib/tailscale"
+      "/var/log"
+    ];
+
+    files = [
+      "/etc/machine-id"
+    ];
+  };
+}

users/tazjin/nixos/modules/zerotier.nix

@@ -0,0 +1,12 @@
+# Configuration for my Zerotier network.
+
+{
+  environment.persistence."/persist".directories = [
+    "/var/lib/zerotier-one"
+  ];
+
+  services.zerotierone.enable = true;
+  services.zerotierone.joinNetworks = [
+    "35c192ce9bd4c8c7"
+  ];
+}