The existing EXTI IRQ handlers are moved from `stm32_it.c` to `extint.c` to
keep them with related code. A macro is defined to make it easier to
define the handler function that handles one line, and correct handlers
added for STM32H5xx MCUs.
Also, to prevent errors in the future, `MP_STATIC_ASSERT(<irqn> > 0)` is
added to each handler function to check that the correct `IRQn` constant is
used, which corresponds to the handler function name.
Signed-off-by: Damien George <damien@micropython.org>
23bfa95d34