Poseidon circomlib

[themighty1]

This PR adds a functionality to compute a Poseidon hash compatible with https://github.com/iden3/circomlib/blob/master/circuits/poseidon.circom

The build script generates the Poseidon constants and writes them to file.

[codecov]

Codecov Report

Attention: Patch coverage is 59.67742% with 25 lines in your changes missing coverage. Please review.

Project coverage is 55.96%. Comparing base (c03418a) to head (acb2ca8).

Files with missing lines	Patch %	Lines
...tes/components/poseidon-circomlib/src/generated.rs	59.25%	11 Missing ⚠️
crates/components/poseidon-circomlib/src/lib.rs	45.00%	11 Missing ⚠️
crates/components/poseidon-circomlib/src/spec.rs	80.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev     #670      +/-   ##
==========================================
+ Coverage   55.95%   55.96%   +0.01%     
==========================================
  Files         189      192       +3     
  Lines       20813    20875      +62     
==========================================
+ Hits        11646    11683      +37     
- Misses       9167     9192      +25     

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[themighty1]

Sorry, the last force-push was me pressing the "Update with rebase" button. I was expecting GH to show that it made the rebase, not I.

[yuroitaki]

nice work! love the generic implementation that caters for all rates up to 16 :)

[yuroitaki]

LGTM!