Bug: Not correct Default system language load for MessageFormatExtensions

[XTorLukas]

Description

The system language is incorrectly defined, a problem occurs when Formater takes the default 'en' for parsing

Screenshot problem

1. If I don't choose the exact language
   
2. Language not set to system language
   
3. This causes the plural localization to function incorrectly
   

Steps To Reproduce

1. If not specified default language load OS default correctly

[XTorLukas]

We overlooked this because I had it selected explicitly, but I have a quick workaround

[XTorLukas]

It would be enough for this method to be static

Files/src/Files.App/ViewModels/Settings/GeneralViewModel.cs

Lines 146 to 163 in b2863a3

	private void AddSupportedAppLanguages()
	{
	var appLanguages = ApplicationLanguages.ManifestLanguages
	.Append(string.Empty) // Add default language id
	.Select(language => new AppLanguageItem(language))
	.OrderBy(language => language.LanguagID is not "") // Default language on top
	.ThenBy(language => language.LanguageName);
	AppLanguages = new ObservableCollection<AppLanguageItem>(appLanguages);
	// Add default language
	var osDefaultLanguage = new AppLanguageItem(CultureInfo.InstalledUICulture.Name);
	if (AppLanguages.Select(language => language.LanguageName.Contains(osDefaultLanguage.LanguageName)).Any())
	AppLanguages[0].LanguagID = osDefaultLanguage.LanguagID;
	string languageID = ApplicationLanguages.PrimaryLanguageOverride;
	SelectedAppLanguageIndex = AppLanguages
	.IndexOf(AppLanguages.FirstOrDefault(dl => dl.LanguagID == languageID) ?? AppLanguages.First());
	}

And then you could just use a similar condition for 'en' instead of CultureInfo.InstalledUICulture and store it in ApplicationLanguages.PrimaryLanguageOverride, I just don't know what the convention is for adding it to the App start method

Files/src/Files.App/Extensions/MessageFormatExtensions.cs

Line 18 in b2863a3

private static readonly CultureInfo locale = ApplicationLanguages.PrimaryLanguageOverride == string.Empty ? CultureInfo.InstalledUICulture : new(ApplicationLanguages.PrimaryLanguageOverride);