Add kl27z_onekey project initial files
- [DBH] keyboard/kl27z_onekey/Makefile
- [DBH] keyboard/kl27z_onekey/README.md
- [DBH] keyboard/kl27z_onekey/boards/ELF/board.c
- [DBH] keyboard/kl27z_onekey/boards/ELF/board.h
- [DBH] keyboard/kl27z_onekey/boards/ELF/board.mk
- [DBH] keyboard/kl27z_onekey/chconf.h
- [DBH] keyboard/kl27z_onekey/config.h
- [DBH] keyboard/kl27z_onekey/halconf.h
- [DBH] keyboard/kl27z_onekey/kl27z.c
- [DBH] keyboard/kl27z_onekey/mcuconf.h