These are intended to replace MICROPY_EVENT_POLL_HOOK and
MICROPY_EVENT_POLL_HOOK_FAST, which are insufficient for tickless ports.
This implementation is along the lines suggested here:
https://github.com/micropython/micropython/issues/12925#issuecomment-1803038430
Currently any usage of these functions expands to use the existing hook
macros, but this can be switched over port by port.
This work was funded through GitHub Sponsors.
Signed-off-by: Angus Gratton <angus@redyak.com.au>