We need loggers

### Search before asking

- [x] I searched the [issues](https://github.com/alibaba/async_simple/issues) and found no similar issues.

### What happened + What you expected to happen

Currently async_simple lacks logger subsystem to log events. Although we don't want async_simple to depend too many things, we should try to make async_simple to depend some loggers conditionally.

### Are you willing to submit a PR?

- [x] Yes I am willing to submit a PR!

No files, tests, or entry points are named. Start by reviewing the async_simple repository structure and existing dependency conventions, then determine the intended logger scope and conditional dependency requirements. Done should mean an agreed logger subsystem design with clear integration and dependency boundaries.

Written by the indexing model from the issue text.