getAdvertisingId static method
Return GoogleAdvertisingId (if using FCM) or AOID (if using HMS)
NOTE: Since late 2021, if user opts out of Ad personalization, FCM ad_id will return bunch of zeros or empty
Implementation
static Future<String> getAdvertisingId() async {
if(!Platform.isAndroid) return "";
return await _channel.invokeMethod("Pushe.getAdvertisingId") ?? "";
}