[Audit] Address Audit Issues and Suggestions

Summary

Human Summary

This PR addresses Issues A and B by providing extra documentation related to the usage of hashing algorithms and the writability of the key-value store. As these are related to the usage of the SMT documentation guidance on best practices for the security of the trie is needed.

Suggestions 1 and 3 have been addressed with the consolidation of the ClosestProof verification method's API and the way in which ExtentionNodes are created with regards to the usage of shared pointers.

AI Summary

reviewpad:summary

Issue

Fixes N/A

Audit Report: Audit Report.pdf

Type of change

Please mark the relevant option(s):

[ ] New feature, functionality or library
[ ] Bug fix
[x] Code health or cleanup
[x] Documentation
[ ] Other (specify)

Testing

[x] Run all unit tests: make test_all
[ ] Run all/relevant benchmarks (if optimising): make benchmark_{all | suite name}

Required Checklist

[x] I have tested my changes using the available tooling
[x] I have performed a self-review of my own code
[x] I have commented my code (godoc format comments see: tip.golang.org/doc/comment)

If Applicable Checklist

[ ] I have added tests that prove my fix is effective or that my feature works
[x] I have updated any relevant README(s)/documentation and left TODOs throughout the codebase
[ ] Add or update any relevant or supporting mermaid diagrams

Codecov Report

Attention: Patch coverage is 76.00000% with 12 lines in your changes are missing coverage. Please review.

Project coverage is 82.87%. Comparing base (8682379) to head (46dc5c5).

Files	Patch %	Lines
proofs.go	57.14%	12 Missing :warning:

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #42 +/- ## ========================================== - Coverage 83.15% 82.87% -0.28% ========================================== Files 9 9 Lines 1460 1489 +29 ========================================== + Hits 1214 1234 +20 - Misses 185 194 +9 Partials 61 61 ```

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pokt-network / smt