esp_wifi_ap_get_sta_aid() function

- ESP_OK: succeed - ESP_ERR_WIFI_NOT_INIT: WiFi is not initialized by esp_wifi_init - ESP_ERR_INVALID_ARG: invalid argument - ESP_ERR_NOT_FOUND: Requested resource not found - ESP_ERR_WIFI_MODE: WiFi mode is wrong - ESP_ERR_WIFI_CONN: WiFi internal error, the station/soft-AP control block is invalid