closes: #644

This PR:

• do not panic for index out of bounds. Instead return Internal error.
• add check for consistency of multiplicity. Return Argument error instead of Internal error when multiplicity is inconsistent.
• Move tests from advz.rs to advz/test.rs. The only actual change to tests is the addition of a new test verify_share_with_different_multiplicity.
• @akonring do you know what's up with these TODOs?

  • jellyfish/vid/src/advz.rs

    Line 535 in e18f3bc

    // TODO: check all indices that represents the shares

  • jellyfish/vid/src/advz.rs

    Line 914 in e18f3bc

    evals_proof: all_evals_commit // TODO: check MT lookup for each index

Before we can merge this PR, please make sure that all the following items have been
checked off. If any of the checklist items are not applicable, please leave them but
write a little note why.

• Targeted PR against correct branch (main)
• Linked to GitHub issue with discussion and accepted design OR have an explanation in the PR that describes this work.
• Wrote unit tests
• Updated relevant documentation in the code
• Added relevant changelog entries to the CHANGELOG.md of touched crates.
• Re-reviewed Files changed in the GitHub PR explorer