feat: handle len(p)=0 in kzg

[ThomasPiellard]

Description

• Kzg Commit now accepts empty slice
• Kzg verifiers now check the validity of the points (commitment and quotients)

Type of change

• 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

How has this been tested?

Please describe the tests that you ran or implemented to verify your changes. Provide instructions so we can reproduce.

• TestVerifySinglePoint

Checklist:

• 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
• I have added tests that prove my fix is effective or that my feature works
• I did not modify files generated from templates
• golangci-lint does not output errors locally
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules