enable using `check` functions on gzipped files for VASP

[matthewkuner]

Summary

Use methods from monty to enable usage of the check() functions in Custodian handlers/validators on compressed files. This is (primarily) meant to enable us to use Custodian handlers/validators when validating VASP calculations for the Materials Project Database.

[janosh]

Thanks @matthewkuner. It might even make sense to do this in pymatgen, i.e. have Incar.from_file("INCAR") always look for INCAR.gz if INCAR is not found. Ofc @shyuep's decision if he wants to weigh in.

[shyuep]

I don't have an issue with this of course.