Description

There are two BigIntegerExtension.ModInverse implementations.
One in Neo.Extensions.BigIntegerExtension, and another in Neo.Vm.Utility.

BigIntegerExtension.ModInverse returns a wrong result if value < 0(always return 0), but it's only used when get public key from private key, so no negative case.

Negative value is not allowed in Neo.Vm.Utility.ModInverse.

This PR removes duplicated implementation and keeps the Neo.Vm.Utility.ModInverse one(and move it to BigIntegerExtension)

Type of change

• Optimization (the change is only an optimization)
• Style (the change is only a code style for better maintenance or standard purpose)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules