re-integrate sample counter check in pymmcore-plus version

[jeskesen]

It's useful to still call check_num_counter_samples in a pre-hardware hook function - some MM devices (like the TriggerScope) have a limit to the length of the sequence you can do and would split one sequence into two if it's two long. The DAQ is not set up to do such splits and the acquisition would run into problems. It seems to me check_num_counter_samples is not called in the current version, I'd suggest bringing it back

Originally posted by @ieivanov in #196 (review)