FasterLog - Commit failed with error code 87 with windows (relative path on a 4k sector disk)

[peterwishart]

I found that running the samples on windows failed on some drives with:

FASTER.core.CommitFailureException: 'Commit of address range [xxx-yyy] failed with error code 87'

Turns out that the sector size defaults to 512 if a relative path is used to initialise FasterLog local storage.
Probably unlikely in production on windows due to where most apps store data.

I tested a fix locally, let me know if I should PR it.