[relay] Feature/relay integration (#2244)

This update adds new relay integration for NetBird clients. The new relay is based on web sockets and listens on a single port.

- Adds new relay implementation with websocket with single port relaying mechanism
- refactor peer connection logic, allowing upgrade and downgrade from/to P2P connection
- peer connections are faster since it connects first to relay and then upgrades to P2P
- maintains compatibility with old clients by not using the new relay
- updates infrastructure scripts with new relay service

relay/client/addr.go

@@ -0,0 +1,13 @@
+package client
+
+type RelayAddr struct {
+	addr string
+}
+
+func (a RelayAddr) Network() string {
+	return "relay"
+}
+
+func (a RelayAddr) String() string {
+	return a.addr
+}