[Feature Request]: Add the F439ZI in future configs

[trainfozz]

Problem/idea statement

As the DCC-EX team in the near future starts testing the Nucleo F429ZI board it may be handy to add also the F439ZI in the dev configs. Those boards are exactly the same with the exception that the F439ZI can do crypto.

Alternatives or workarounds

Taken from the DCCTimerSTM32.ccp:

current: #elif defined(ARDUINO_NUCLEO_F412ZG) || defined(ARDUINO_NUCLEO_F429ZI) || defined(ARDUINO_NUCLEO_F446ZE)

suggested: #elif defined(ARDUINO_NUCLEO_F412ZG) || defined(ARDUINO_NUCLEO_F429ZI) || defined(ARDUINO_NUCLEO_F439ZI) || defined(ARDUINO_NUCLEO_F446ZE)

Additional context

As I do own a F439ZI I can be a beta-tester for the F439ZI if required.