gpio_new_etm_event() function

- ESP_OK: Create ETM event successfully - ESP_ERR_INVALID_ARG: Create ETM event failed because of invalid argument - ESP_ERR_NO_MEM: Create ETM event failed because of out of memory - ESP_ERR_NOT_FOUND: Create ETM event failed because all events are used up and no more free one - ESP_FAIL: Create ETM event failed because of other reasons

The created ETM event object can be deleted later by calling `esp_etm_del_event` The newly created ETM event object is not bind to any GPIO, you need to call `gpio_etm_event_bind_gpio` to bind the wanted GPIO Every success call to this function will acquire a free GPIO ETM event channel