Switch from golang.org/x/net/websocket to nhooyr.io/websocket and handle NotFound errors (#105)

* Switch from golang.org/x/net/websocket to nhooyr.io/websocket

* Do not attach errors that we can handle to the Gin's context

* Add missing newline to "no credentials specified or found, ..." message

* Fix potential NPE in ChooseUsernameAndPassword()

* Fix type in PortForward() error message in "orchard ssh vm"

* Fix potential NPE in Connections()

* Use header.Set() for consistency's sake for Authorization header

internal/command/vnc/vm.go

@@ -72,6 +72,7 @@ func runVNCVM(cmd *cobra.Command, args []string) (err error) {
 
 					return
 				}
+				defer wsConn.Close()
 
 				if err := proxy.Connections(wsConn, conn); err != nil {
 					fmt.Printf("failed to forward port: %v\n", err)