Key share refreshing ceremony refactor

[piotr-roslaniec]

Type of PR:

• Refactor
• Feature

Required reviews:

• 1

What this does:

• Attempts to hide some of the cryptographic primitives behind newtype structs
• This in turn caused some yet unsolved problems with serde
  • serde can't handle serde_as for crate::* for some reason. external_crate::* works just fine
• Adds intermediate design for refreshing and recovery API. No bindings yet, to be done after other changes (verification) take place.
  • PrivateKeyShare and its derivatives used in refreshing and recovery are now a part of the public API. This should help decouple them from AggregateTranscript.
  • The "legacy" methods for creating decrypting shares etc., through AggregateTranscript are not deprecated yet - Awaiting more details on a new design, to be addressed in future PR.

Issues fixed/closed:

• Fixes Protocol objects and methods for handling share updates between participants #162

Why it's needed:

Explain how this PR fits in the greater context of the NuCypher Network.
E.g., if this PR address a nucypher/productdev issue, let reviewers know!

Notes for reviewers:

• This PR is based on Relax DKG ceremony constraints #173 - Please review it first
• Created Design protocol & related structures for onboarding and offboarding validators #181

[codecov-commenter]

Codecov Report

Attention: 121 lines in your changes are missing coverage. Please review.

Comparison is base (72b8484) 78.28% compared to head (779a7bb) 79.76%.
Report is 1 commits behind head on main.

Files	Patch %	Lines
ferveo/src/bindings_python.rs	63.15%	49 Missing ⚠️
ferveo/src/api.rs	92.81%	47 Missing ⚠️
ferveo-tdec/src/decryption.rs	26.31%	14 Missing ⚠️
ferveo/src/bindings_wasm.rs	0.00%	5 Missing ⚠️
ferveo/src/refresh.rs	98.67%	3 Missing ⚠️
ferveo/src/dkg.rs	97.70%	2 Missing ⚠️
ferveo-common/src/keypair.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #175      +/-   ##
==========================================
+ Coverage   78.28%   79.76%   +1.47%     
==========================================
  Files          24       24              
  Lines        5066     5856     +790     
==========================================
+ Hits         3966     4671     +705     
- Misses       1100     1185      +85     

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[cygnusv]

Approved! This is the foundation for the work for Refresh & Recovery, laying out a better codebase to accommodate the required changes