This commit creates a new stm32 board for the NUCLEO_H743ZI2, which is the
current version of this from ST. This is a modified copy of the
NUCLEO_H743ZI board, and the ZI2 board differs in a few minor ways:
- LED2 has moved from PB7 to PE1 and is now yellow rather than blue
- the USB power enable has moved from PG6 to PG10
- the USER button is now pulled down
