dedic_gpio_get_out_mask() function

- ESP_OK: Get channel mask successfully - ESP_ERR_INVALID_ARG: Get channel mask failed because of invalid argument - ESP_FAIL: Get channel mask failed because of other error

Each bundle should have at least one mask (in or/and out), based on bundle configuration. With the returned mask, user can directly invoke LL function like "dedic_gpio_cpu_ll_write_mask" or write assembly code with dedicated GPIO instructions, to get better performance on GPIO manipulation.