Feat: Support passing in enums into TypedExtras

[farmery]

Summary

This PR introduces support for passing Enum fields into custom annotations that extend TypedExtras. Developers can now pass Enum fields in the custom class extending TypedExtras. These Enum fields are automatically converted into their string representations and included in the extras map.

Example

enum FileType { json, xml, csv }

@TypedExtrasSubClass(
  id: '1234',
  fileType: FileType.json,
)
Future<String> fetchData(@Extras() Map<String, dynamic> extras);

[trevorwang]

Thanks for the contribution