Returns one alternative of a language alternative such as dc:title.
public string? GetLanguageAlternative(string namespaceName, string name, string? language = null)
The namespace name.
The local name.
The language wanted, such as de; null for the default.
xml:lang is language (compared without case), else the x-default item, else the
first item; the value itself when the property is simple; null when absent.
ISO 16684-1 §8.2.2.4.