🧑‍💻(docker) split frontend to another file

This commit aims at improving the user experience:
- Use a dedicated `Dockerfile` for the frontend
- Run the backend and frontend in "watch"/dev mode in Docker
- Do not start all Docker instances for small tasks

docker/auth/realm.json

@@ -26,7 +26,7 @@
   "oauth2DeviceCodeLifespan": 600,
   "oauth2DevicePollingInterval": 5,
   "enabled": true,
-  "sslRequired": "external",
+  "sslRequired": "none",
   "registrationAllowed": true,
   "registrationEmailAsUsername": false,
   "rememberMe": true,