device.geo.country is being sent in iso alpha-2 format

[justadreamer]

Describe the bug
We noticed that device.geo.country is populated from carrier data and is sent in alpha-2 format, while OpenRTB spec demands it to be in alpha-3 format, see [here].(https://github.com/InteractiveAdvertisingBureau/openrtb2.x/blob/main/2.6.md#:~:text=ISO%2D3166%2D1-,%2Dalpha%2D3,-.)

To Reproduce
Intercept a request from a demo app running on a physical device using Charles and check device.geo.country.
It is in alpha-2 format.

Expected behavior
device.geo.country should not be populated by the SDK from the carrier data as it is expected to be populated from reverse-geocoding the coordinates if they are sent on the server. iOS does not populate this field. However if we choose to populate it then it should be in alpha-3 format as OpenRTB spec requires.

Additional context
Additionally @takenorim has pointed out the following details:

I found the Prebid Mobile Android SDK uses Android's native API getSimCountryIso or getNetworkCountryIso.
And, the API doc said it will return ISO-3166-1 alpha-2 country code (e.g. US)

In prebid-mobile-android/PrebidMobile/PrebidMobile-core/src/main/java/org/prebid/mobile/rendering/networking/parameters/GeoLocationParameterBuilder.java:

    private String getTelephonyCountry(Context ctx){
        TelephonyManager tm = (TelephonyManager) ctx.getSystemService(Context.TELEPHONY_SERVICE);


        if(tm != null) {
            String simCountry = tm.getSimCountryIso().toUpperCase();
            String networkCountry = tm.getNetworkCountryIso().toUpperCase();

The first one returns the ISO-3166-1 alpha-2 country code equivalent for the SIM provider's country code.
The second one returns the ISO-3166-1 alpha-2 country code equivalent of the MCC (Mobile Country Code) of the current registered operator or the cell nearby, if available. Note: Result may be unreliable on CDMA networks (use getPhoneType() to determine if on a CDMA network)

The following changes may fix it:

In prebid-mobile-android/PrebidMobile/PrebidMobile-core/src/main/java/org/prebid/mobile/rendering/networking/parameters/GeoLocationParameterBuilder.java:

            String simCountry = tm.getSimCountryIso().toUpperCase();
            String networkCountry = tm.getNetworkCountryIso().toUpperCase();

=>

            String simCountry = (new Locale("en", tm.getSimCountryIso()).getISO3Country()).toUpperCase();
            String networkCountry = (new Locale("en", tm.getNetworkCountryIso()).getISO3Country()).toUpperCase();

However it is debatable whether we should even send this as this data is expected to be obtained from the coordinates via reverse-geocoding rather than carrier.