Add STM32CubeProgrammer where it is not available, & make it
default flashing method by placing it 1st in board.cmake
Before this change, the west runner that's selected when calling
'westflash' without the '--runner ...' option is kind of arbitrary
& depends on which runner is 1st in board.cmake file.
Another reason this change is needed is that STM32CubeProg is the only
available way to check/modify Option Bytes, and to flash code to
external Flash on many STM32 boards.
This change does not affect 'west debug' behavior, which defaults to
the debugger (OpenOCD/JLink) that is included first in board.cmake
Signed-off-by: Abderrahmane Jarmouni <git@jarmouni.me>
