Check for enough space to perform benchmark before starting

[jamesmarkchan]

if doing a benchmark on a drive wo enough space it will still start and error out when we are out of space, we should make sure we have enough room with margin before starting and notify the user if not enough space.

[jamesmarkchan]

@jslcom in case you are able to help test this build should have a candidate to resolve this issue:

https://github.com/JDiskMark/jdm-java/actions/runs/31462586345