Support unencrypted streams

[Zk2u]

Sometimes, the client and server may already have an encrypted private connection. Double encrypting with TLS is not worth the performance loss in these cases. An example is when not using pure physical network links and instead using a VPN like WireGuard. In production, we use 6PN - an iPv6 WireGuard mesh network - between server instances.

In these cases, encryption is handled outside HardLight. We should support using regular, non-TLS connectors in both the client and the server not to slow this down.