Handle bi-directional communication between server and client

[mostafa]

I suppose this can be done using Go channels.

gatewayd/network/proxy.go

Lines 123 to 127 in da83204

	// TODO: Handle bi-directional traffic
	// Currently the passthrough is a one-way street from the client to the server, that is,
	// the client can send data to the server and receive the response back, but the server
	// cannot take initiative and send data to the client. So, there should be another event-loop
	// that listens for data from the server and sends it to the client

Update:
I've done some initial work in this branch, but most of this is related to server to client communication. Examples of which is NOTIFY command in PostgreSQL, which is not part of the SQL standard.

I'll close this ticket until there's an actual need for this.

[mostafa]

Fixed in #344.