refactor: Improve Spartan SNARK polynomial computations and evaluations

[huitseeker]

Summary

This gathers the changes to the pre-processing SNARK excerpted from the Supernova implementation in PR #283. The main changes extracted here are the introduction of the masked eq polynomial (and its use fixing this issue), additional sum-check tooling, removal of two calls to evaluation argument.

Main reference Arecibo PRs:

• snark.rs: factor out batch evaluation Sumcheck argumentcomputer/arecibo#106
• Supernova CompressedSNARK argumentcomputer/arecibo#131
• Documentation and code duplication in supernova::CompressedSNARK argumentcomputer/arecibo#174
• apply bound witness fix to ppsnark argumentcomputer/arecibo#182

More details (click to expand)

• Enhancement of polynomial related code in Spartan protocol including new polynomial types, modified existing types, better evaluation methods, and improved polynomial operations.
• Introduction of squares function and change in the generation of t_pow in Spartan.
• Addition of a new polynomial type through MaskedEqPolynomial with methods for its creation and evaluation.
• Enhancements in UniPoly struct by addition of PartialEq, and Eq traits.
• Improvements in snark.rs for proving and verifying batch evaluation claims, leveraging gamma and rho for random linear combinations, and optimizing various variable computations.
• Updates in multilinear.rs with refactoring, optimization, error handling, and supplementing unit tests.
• Refactor in spartan/mod.rs with import updates, function overhauls, struct visibility changes, and asynchronous operations for efficient calculations.
• Additions and amendments in sumcheck.rs for batch verification, handling of vectors of claims, handling of cubic bounds with additive terms, visibility adjustments, and typo fixes.
• Modifications in eq.rs including a debug derive for EqPolynomial, enhanced visibility of r vector, provision of evals_from_points for enhanced evaluation, and addition of FromIterator implementation.