[Feature Request]: Check for LELF when setting NCORE or NPAR

[Andrew-S-Rosen]

Problem

When using LELF = .TRUE., the user is supposed to explicitly set NPAR=1. This is noted in the VASP manual and confirmed on the VASP forum. Therefore, in Custodian whenever we change NCORE or NPAR, we should make sure that we are not doing so if LELF = .TRUE.

Proposed Solution

See above.

Alternatives

No response