🎉 Add Nextcloud widget

Add a widget supporting the `capabilites`, `user`
and `serverinfo` Nextcloud APIs.

Basic branding, user and quota information is always displayed
and when the provided credentials are for and admin user then
server information is also displayed.

APIs:
* [capabilities](https://docs.nextcloud.com/server/latest/developer_manual/client_apis/OCS/ocs-api-overview.html#capabilities-api)
* [user](https://docs.nextcloud.com/server/latest/developer_manual/client_apis/OCS/ocs-api-overview.html#user-metadata)
* [serverinfo](https://github.com/nextcloud/serverinfo)

src/assets/locales/en.json

@@ -303,6 +303,10 @@
       "remaining": "Remaining",
       "up": "Up",
       "down": "Down"
+    },
+    "nextcloud-info": {
+      "label-version": "Nextcloud version",
+      "label-last-login": "Last login"
     }
   }
 }