esp_eap_client_set_pac_file() function

Set the PAC (Protected Access Credential) file for EAP-FAST authentication. EAP-FAST requires a PAC file that contains the client's credentials. @attention 1. For files read from the file system, length has to be decremented by 1 byte. @attention 2. Disabling the ESP_WIFI_MBEDTLS_TLS_CLIENT config is required to use EAP-FAST.