Update RegionInfo data and Fix RegionInfo.CurrentRegion on Windows

[tarekgh]

Fixes #32753

Currently when running on Windows, the call of RegionInfo.CurrentRegion will return the region object matching CurrentCulture. Windows has different settings for the default region than the current culture. The good example is mentioned in the scenario in the attached issue which having current culture was set to English (Europ) and Country was set to Netherland and when getting CurrentRegion we return 159 because Europ doesn't have country code (because it is not a country). We suppose to return the region for Netherland.
The change here is fixing this issue and updating the region data table too to reflect latest list of regions we have in the world.

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[tarekgh]

I logged the issue #33875 to track Mono's failures in the CI.
I logged the issue #33876 for the other CI restoring coverlet (dup of #33837)

[tarekgh]

@jkotas @stephentoub please let me know if you have any more feedback or we ok to merge. the failures in the CI are unrelated and tracked with other linked issues.

[danmoseley]

So sometimes it's null terminated and sometimes not? Why does it not return ERROR_INSUFFICIENT_BUFFER when it has no room to null terminate?

[tarekgh]

The doc is not ensuring returning null that is why I have to check to know if we got the null or not.
We are requesting the 2-letters country code and I am providing a buffer of length 10 which is far enough to ensure not running into the ERROR_INSUFFICIENT_BUFFER case even with null.

[jkotas]

From what I can tell, this is always returning zero terminated string.

Would it be best to create the string from the pointer and not bother with using the returned size? I would be fine with not using the Span in that case because of there is no buffer math that can go wrong.

char* pGeoIso2Letters = stackalloc char[10];

if (Interop.Kernel32.GetGeoInfo(..., pGeoIso2Letters, ...) != 0)
{
    CultureData? cd = GetCultureDataForRegion(new string(pGeoIso2Letters), ...

[tarekgh]

I would be more conservative checking null as the doc didn't ensure that and I am not sure what happen if we run on a different version of Windows.

[danmoseley]

nit, I don't think there is any value in passing in a prime number - the dictionary internally rounds up to the next prime number from its list. it's harmless though of course.

Ideally the C# compiler would know that there's N entries coming in the initializer and pass in N to the constructor.

[tarekgh]

I'll keep it as it is harmless and I am not sure what the C# initializer how it behaves there.

[danmoseley]

fine, fyi the initializer always uses the parameterless constructor, so it is a valid microoptmization to pass a size here.

[jkotas]

Thanks