feat: create backups module

We currently have backups via a shell script on the machine
vermilion.bravo. Unfortunately, we can't activate these backups without
setting up a user, and that wasn't done yet for teal.

This commit adds backups, and also enforces their activation by failing
to evaluate if a backups key has not been provided and backups have not
been explicitly disabled.

Change-Id: Ia37bd13cb8de6e20cc77e735630a59cb0c5d0fb4
Reviewed-on: https://git.clicks.codes/c/Infra/NixFiles/+/756
Tested-by: Skyler Grey <minion@clicks.codes>
Reviewed-by: Samuel Shuert <coded@clicks.codes>
diff --git a/modules/nixos/clicks/security/doas/default.nix b/modules/nixos/clicks/security/doas/default.nix
index 424d9d7..9778b00 100644
--- a/modules/nixos/clicks/security/doas/default.nix
+++ b/modules/nixos/clicks/security/doas/default.nix
@@ -28,6 +28,10 @@
           noPass = true;
           keepEnv = true;
         }
+        {
+          users = config.clicks.users.backups;
+          noPass = true;
+        }
       ];
     };