Allow source debugger reconnection (#1667)

Allow to wait for a new debugger connection once the previous one
is disconnected:
- when receiving a detach command
- when the client socket is closed (for example, lldb process is killed)

core/iwasm/libraries/debug-engine/handler.c

@@ -777,3 +777,13 @@ handle____request(WASMGDBServer *server, char *payload)
         handle_free(server, args);
     }
 }
+
+void
+handle_detach_request(WASMGDBServer *server, char *payload)
+{
+    if (payload != NULL) {
+        write_packet(server, "OK");
+    }
+    wasm_debug_instance_detach(
+        (WASMDebugInstance *)server->thread->debug_instance);
+}