Circuit fixes

[saleel]

Description

• Add missing constrains for length input signals
• Fix index off by one in AssertZeroPadding
• Fix param in PoseidonLarge
• Document input assumptions
• Remove unused code
• Remove unnecessary asserts()
• Fix warnings in Fp due to array size

Type of Change

Please delete options that are not relevant.

• 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:

• I have discussed with the team prior to submitting this PR
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• New and existing unit tests pass locally with my changes