Handle peer interface config change (#348)

Before this change, NetBird Agent wasn't handling
peer interface configuration changes dynamically.
Also, remote peer configuration changes have
not been applied (e.g. AllowedIPs changed).
Not a very common cause, but still it should be handled.
Now, Agent reacts to PeerConfig changes sent from the
management service and restarts remote connections
if AllowedIps have been changed.

client/internal/peer/conn.go

@@ -66,6 +66,11 @@ type Conn struct {
 	proxy proxy.Proxy
 }
 
+// GetConf returns the connection config
+func (conn *Conn) GetConf() ConnConfig {
+	return conn.config
+}
+
 // NewConn creates a new not opened Conn to the remote peer.
 // To establish a connection run Conn.Open
 func NewConn(config ConnConfig) (*Conn, error) {
@@ -437,7 +442,7 @@ func (conn *Conn) Close() error {
 		// before conn.Open() another update from management arrives with peers: [1,2,3,4,5]
 		// engine adds a new Conn for 4 and 5
 		// therefore peer 4 has 2 Conn objects
-		log.Warnf("closing not started coonection %s", conn.config.Key)
+		log.Warnf("connection has been already closed or attempted closing not started coonection %s", conn.config.Key)
 		return NewConnectionAlreadyClosed(conn.config.Key)
 	}
 }