Anywise

- add `BaseGuard`, user can inherit from it then override `async def __call__`.
- update docs
- improve command resolve logic

replace GuardRegistry, ListenerRegistry, HandlerRegistry with a new `MessageRegistry`
reduce boilerplace code, make api easier to work with

now will build guards before send, now the order of anywise.include(guard_registry) does not matter

- contexted handler
- command guard