Refactoring Multi-instance Wechaty Design: Try to remove the Accessory class and related codes

The Accessory class is very complicated and has lots of limitations.

For example, all User Class (user/*.ts) have to extend from it, which prevent us to extend from different EventEmitters (types, like using typed-emitter)

So I decided to re-design this part of the code and try to remove all related codes of the Accessory class.