Stub implementation of the SimCurveCryptoPool

[chanhosuh]

Description

Mostly just added comments to the stub class for SimCurveCryptoPool created in #164. It will be handy to branch off this for multiple pieces of work, including:

• Integrate SimCurveCyptoPool with ParametrizedPoolInterator #165
• price #178
• get_input_amount #179

Hygiene checklist

• Changelog entry (no need, as this is start for other work which will have entries)
• Everything public has a Numpy-style docstring
  (modules, public functions, classes, and public methods)
• Pylint score monotonically increased
• Commit history is cleaned-up with minor changes squashed together
  and descriptive commit messages following Tim Pope's style

Cute Animal Picture

[github-actions]

Coverage report

The coverage rate went from 75.57% to 75.48% ⬇️
The branch rate is 63%.

75% of new lines are covered.

Diff Coverage details (click to unfold)

curvesim/pool/sim_interface/cryptoswap.py

64.86% of new lines are covered (58.53% of the complete file).
Missing lines: 18, 20, 21, 22, 23, 32, 38, 67, 96, 97, 98, 120, 141

curvesim/pool/sim_interface/init.py

100% of new lines are covered (100% of the complete file).

curvesim/pool/cryptoswap/calcs/factory_2_coin.py

100% of new lines are covered (84.57% of the complete file).

curvesim/pool/cryptoswap/pool.py

100% of new lines are covered (82.07% of the complete file).

curvesim/pool/cryptoswap/calcs/tricrypto_ng.py

100% of new lines are covered (84.72% of the complete file).