LocaleType change causes hosted payments to default to Arabic language

[Antaris]

The recent change to PaymentLinkRequest to change the LocaleType from a string to LocaleType enum now results in the default value being ar, which is the Arabic language.

Easy work around for us, we can just manually set the locale, but as this isn't documented, it means people upgrading to 4.6.0 may have an unexpected default language if they don't intend to use ar

983b495

Should this be a nullable property instead, so semantically the same as a nullable string:

public LocaleType? Locale { get; set; }

[armando-rodriguez-cko]

Of course, it is a mistake, thank you @Antaris