TwoLetterISOLanguageName is insufficient for loading localized documentation

[sharwell]

The following two locations assume that localized documentation for the zh-Hans culture for path/to/A.dll will be located at path/to/zh/A.xml. In reality, the file may be located at path/to/zh-Hans/A.xml. These locations should be updated to look under a directory named CultureInfo.Name for documentation, and only fall back to checking for CultureInfo.TwoLetterISOLanguageName if the more specific check fails.

ILSpy/ICSharpCode.Decompiler/Documentation/XmlDocLoader.cs

Lines 113 to 114 in 2e8bde9

	string currentCulture = System.Threading.Thread.CurrentThread.CurrentUICulture.TwoLetterISOLanguageName;
	string localizedXmlDocFile = GetLocalizedName(xmlFileName, currentCulture);

ILSpy/ICSharpCode.Decompiler/Documentation/XmlDocumentationProvider.cs

Lines 206 to 207 in 2e8bde9

	string currentCulture = System.Threading.Thread.CurrentThread.CurrentUICulture.TwoLetterISOLanguageName;
	string localizedXmlDocFile = GetLocalizedName(xmlFileName, currentCulture);

📝 It may also be possible to consolidate these two locations.

🔗 Discovered during a review of this user-reported issue:
https://developercommunity.visualstudio.com/t/The-annotation-information-of-the-class-/10288684