#181 add tera filter sha256_hash

[krysopath]

This PR wants to add a new tera filter function for repeated sha256 hashes with an optional salt.

This intends not to be a solution for highly confidential secret, rather to provide a way of having a value in the output that can be verified when the salt is known.

For highly confidential values a more flexible hash should be used.

✓ Checklist:

• This PR has been added to CHANGELOG.md (at the top of the list);
• Tests for the changes have been added (for bug fixes / features);
• Docs have been added / updated (for bug fixes / features).

[codecov-commenter]

Codecov Report

Merging #185 (746d79c) into main (522cc42) will increase coverage by 0.20%.
The diff coverage is 97.36%.

@@            Coverage Diff             @@
##             main     #185      +/-   ##
==========================================
+ Coverage   86.58%   86.78%   +0.20%     
==========================================
  Files          57       57              
  Lines        4010     4086      +76     
==========================================
+ Hits         3472     3546      +74     
- Misses        538      540       +2     

Impacted Files	Coverage Δ
...engine/src/transformers/template/hash_functions.rs	95.61% <97.36%> (+3.50%)	⬆️

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[evgeniy-r]

Hello!

Thank you for your contribution, is this PR ready (it is marked as draft)? If so, please update CHANGELOG.md and docs (near https://github.com/datanymizer/datanymizer/blob/main/docs/transformers.md#crypto) and I will merge the PR.

[krysopath]

Hello @evgeniy-r ,

I was caught in internal discussion about disclosing our production db scheme to help debugging #178. Also there were suggestions of adding HMAC tera function for a "more secure" hashing. What do you think about adding HMAC in another PR?

I will update docs, changelog and undraft today.

[evgeniy-r]

Yes, you can add HMAC too. It would be great.