fix(ext/net): Improve ts types for network APIs (#23228)

This currently fails to type-check in deno, but we know that listener is
a `Listener<TcpConn>` here and we should be able to improve the typing:

```
let listener = Deno.listen({ port: 0 });
console.log(listener.addr.port);

->

error: TS2339 [ERROR]: Property 'port' does not exist on type 'Addr'.
  Property 'port' does not exist on type 'UnixAddr'.
let listener = Deno.listen({ port: 0 }); console.log(listener.addr.port)
```

After:

```
Check file:///tmp/test.ts
```

0 files changed, 0 insertions, 0 deletions