LibUnicode: Add public wrapper for the generated locale_from_string

Author: https://github.com/trflynn89
Commit: 12ae0a44d7
Pull-request: https://github.com/SerenityOS/serenity/pull/9841
Reviewed-by: https://github.com/IdanHo
Reviewed-by: https://github.com/linusg ✅

Userland/Libraries/LibUnicode/Locale.h

@@ -119,6 +119,7 @@ Optional<String> canonicalize_unicode_locale_id(LocaleID&);
 
 String const& default_locale();
 bool is_locale_available(StringView locale);
+Optional<Locale> locale_from_string(StringView locale);
 
 Optional<StringView> get_locale_language_mapping(StringView locale, StringView language);
 Optional<StringView> get_locale_territory_mapping(StringView locale, StringView territory);