Small changes to pre-check functions

Change the input ```drive``` to ```path``` and write the test file to the ```local_storage_dir``` and ```ext_storage_dir```. Also can rename the filename from ```test.txt``` to just ```test```.

https://github.com/AllenNeuralDynamics/spim-core/blob/b8d9529f10c8a2e9ec3c3247ba3770fbf5a79995/spim_core/spim_base.py#L141-L192

Also change the previous check memory resources function to public.