[Enhancement] Add DeviceInfo.CurrentCulture to get language currently selected on device

[maxkoshevoi]

Hi, I initially created the issue and PR, but I think it would fit better in essentials.
Would you accept such feature here? If so, I'll retarget that PR to here.

Summary

If user changes device language while app is running, CultureInfo.CurrentCulture and other ways to see current culture won't be updated, and continue to return device language that was set during app start.

API Changes

• CultureInfo DeviceInfo.CurrentCulture { get; }

Intended Use Case

Get language currently selected on device for app localization:

protected override void OnStart()
{
    LocalizationResourceManager.Current.CurrentCulture = DeviceInfo.CurrentCulture;
}

[dimonovdd]

I think this functionality goes beyond essentials. localization has a lot of things that depend on the specific application

[maxkoshevoi]

@dimonovdd what do you mean by "goes beyond essentials"? Do you mean that this PR should be open in Xamarin.Forms repository instead?

[dimonovdd]

This needs to be configured in each specific application

[maxkoshevoi]

@dimonovdd What needs to be configured? This feature request if only for API to get current device language. There is no configuration needed for it to work.

[dimonovdd]

I did a little review on your PR

[AmrAlSayed0]

There was a PR #336 a long time ago but it wasn't accepted due to lack of a common API surface.

[maxkoshevoi]

@AmrAlSayed0 Wow, that's awesome, thank you! Maybe we can just redirect that PR in XCT as "better than nothing solution"? XCT doesn't need to support all platforms or have prefect API.