Proxy should support port streaming

[GyulyVGC]

nullnet-proxy should support streaming ports.

Note

This was requested by Kevin:
It would be great if the app could support proxying TCP and UDP traffic similar to NGINX's stream block.
This would allow exposing services like PostgreSQL, Redis, SSH, MQTT, or game servers directly through the app without relying on an external reverse proxy.
It would be a really useful addition for self-hosted and production environments.