board: arm: nucleo-l4r5zi: flashing with STM32CubeProgrammer

[ajarmouni-st]

This patch adds the possibility to flash nucleo-l4r5zi board using STM32CubeProgrammer.

[kartben]

Beyond the mentioned typo, and as a non-blocking comment, it looks like it might make sense to extract some common "ST board flashing instructions" doc snippets (a la

zephyr/boards/x86/intel_adl/doc/up_squared_pro_7000.rst

Lines 69 to 71 in c25ac48

	.. include:: ../../common/efi_boot.rst
	:start-after: start_include_here

) so that instructions are somewhat consistent between boards.

IMO aiming for something like

zephyr/boards/arm/nucleo_u575zi_q/doc/index.rst

Lines 246 to 260 in c25ac48

	Board is configured to be flashed using west STM32CubeProgrammer runner.
	Installation of `STM32CubeProgrammer`_ is then required to flash the board.
	Alternatively, openocd (provided in Zephyr SDK), JLink and pyocd can also be
	used to flash and debug the board if west is told to use it as runner,
	which can be done by passing either ``-r openocd``, ``-r jlink`` or ``-r pyocd``.
	For pyocd additional target information needs to be installed.
	This can be done by executing the following commands.
	.. code-block:: console
	$ pyocd pack --update
	$ pyocd pack --install stm32u5

where all the potential flashing options and their specificities would be nice, i.e. in the current PR it feels like the proposed wording assumes that only stm32cubeprogrammer is supported. Maybe you can at least clarify that bit, and briefly mention other available options (openocd and jlink)?

[erwango]

Beyond the mentioned typo, and as a non-blocking comment, it looks like it might make sense to extract some common "ST board flashing instructions" doc snippets

Thanks @kartben for the suggestion. We'll work on that.