gpio_new_etm_task() function

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

The created ETM task object can be deleted later by calling `esp_etm_del_task` The GPIO ETM task works like a container, a newly created ETM task object doesn't have GPIO members to be managed. You need to call `gpio_etm_task_add_gpio` to put one or more GPIOs to the container. Every success call to this function will acquire a free GPIO ETM task channel