nixos/nextcloud: enable apc cache for cli if apcu is enabled

As described in the admin manual[1] of Nextcloud.

[1] https://docs.nextcloud.com/server/21/admin_manual/configuration_server/caching_configuration.html#id1

nixos/modules/services/web-apps/nextcloud.nix

@@ -28,7 +28,10 @@ let
     upload_max_filesize = cfg.maxUploadSize;
     post_max_size = cfg.maxUploadSize;
     memory_limit = cfg.maxUploadSize;
-  } // cfg.phpOptions;
+  } // cfg.phpOptions
+    // optionalAttrs cfg.caching.apcu {
+      "apc.enable_cli" = "1";
+    };
 
   occ = pkgs.writeScriptBin "nextcloud-occ" ''
     #! ${pkgs.runtimeShell}