Convert bongo-cat to zmk module instead of keeping zmk fork

[duynguyenhoang]

Thank you for your init work.
Currently you are keeping zmk fork and add new feature on top. But there would be a better way to do it by using zmk module.
Basically it is just a new shield.
There is another work here https://github.com/mctechnology17/zmk-nice-oled. You can prefer to his work.

[SamIAm2000]

I'll look into it, thanks!