feat: add groups to authentik apps + add mail base

modules/containers.nix

@@ -65,6 +65,11 @@ in
                   description = "Overrides to the Proxmox LXC Terraform resource";
                   default = { };
                 };
+                onboot = mkOption {
+                  type = bool;
+                  default = true;
+                  description = "Boot at Proxmox's startup";
+                };
                 protection = mkOption {
                   type = bool;
                   description = "Whether container should be protected against changes.";
@@ -174,6 +179,11 @@ in
             description = "Possible description for the service";
             default = null;
           };
+          group = mkOption {
+            type = nullOr str;
+            description = "Group for the service (on Authentik)";
+            default = null;
+          };
           icon = mkOption {
             type = nullOr str;
             description = "URL for a logo for the service";