Add configuration item api->listen. (#3317)

* add api.listen configuration item

* add unit tests

* typo

---------

Co-authored-by: nobody <nobody@nowhere.mars>

app/commander/config.proto

@@ -12,6 +12,10 @@ import "common/serial/typed_message.proto";
 message Config {
   // Tag of the outbound handler that handles grpc connections.
   string tag = 1;
+
+  // Network address of commander grpc service.
+  string listen = 3;
+
   // Services that supported by this server. All services must implement Service
   // interface.
   repeated xray.common.serial.TypedMessage service = 2;