feature: add type hint to event.py, row_event.py, binlogfilereader.py

Co-authored-by:    suhwan-cheon <soo7652@naver.com>
Co-authored-by:    ebang091 <dskhe8@gmail.com>
Co-authored-by:    yangbaechu <abab_1212@naver.com>
Co-authored-by:    jaehyeonpy <jaehyeonpy@gmail.com>

Author: 4 people