[Opact] Correcting issues from Kadena Review

[1Mateus]

Correct the following issues:

• The usage of several formal verification annotations is noted, but nothing is checked against.
• The Interface (gas-payer-v1) and Verifier (groth16-verifier) have no comments please add. Additionally, the test suite requires more explanatory comments.
• The MerkleTree contract has no comments, and it’s difficult to ascertain the origins and meanings of various hashes and values, such as those in poseidon-zeros and blake-zeros. The tests focus solely on successful scenarios (using ‘except’) and neglect failure cases (which would use ‘expect-failure’).
• The repository’s contracts directory includes redundant or outdated files, like the poseidon directory.
• The contract ‘opact’ has no explanatory comments, requires a description. The tests in ‘transact-tests.repl’ feature numerous commented-out lines, and there requires more test cases. Overall, there is an almost complete absence of code comments.
• The test cases could benefit from being more comprehensive.
• The reliance on JavaScript for generating contracts and files may not be the best approach. While it can be utilized for initial generation, the final versions should be committed to the repository.
• The project structure, as outlined in the Readme.md, seems incomplete. It fails to mention certain aspects like ‘transact’, for example.