feat: fuzzy converters

[WieeRd]

One of the signature feature of ClockBot is smart target recognition via fuzzy matching nicknames.
I plan to separate this feature as a library and improve some aspects of it.

• Hangul specialization - 초성 검색 https://github.com/WieeRd/ricecake
• Better typing - Use typing.Annotated instead of weird subclassing
• Accuracy - Explore different sorting priorities
• Performance - Run matching / sorting in parallel
• Extension - Can be used outside just nickname matching, such as invoking command.