esp_bt_gap_start_discovery() function

This function starts Inquiry and Name Discovery. This function should be called after esp_bluedroid_enable() completes successfully. When Inquiry is halted and cached results do not contain device name, then Name Discovery will connect to the peer target to get the device name. esp_bt_gap_cb_t will be called with ESP_BT_GAP_DISC_STATE_CHANGED_EVT when Inquiry is started or Name Discovery is completed. esp_bt_gap_cb_t will be called with ESP_BT_GAP_DISC_RES_EVT each time the two types of discovery results are got.