LibUnicode: Generate a list of available numbering systems

Author: https://github.com/trflynn89
Commit: 481ced53d8
Pull-request: https://github.com/SerenityOS/serenity/pull/12223
Reviewed-by: https://github.com/linusg ✅

Userland/Libraries/LibUnicode/NumberFormat.h

@@ -66,6 +66,8 @@ enum class NumericSymbol : u8 {
     PlusSign,
 };
 
+Span<StringView const> get_available_number_systems();
+
 Optional<NumberSystem> number_system_from_string(StringView system);
 Optional<StringView> get_default_number_system(StringView locale);