[WIP] Generate shared secret test vectors

[Muhammad-Altabba]

Type of PR:

• Bugfix
• Feature
• Documentation
• Other

Required reviews:

• 1
• 2
• 3

What this does:
As part of: nucypher/taco-web#635, implement tests that generate shared secrets encrypt/decrypt values to check the TS implementation agains them.
Also README.md file has been updated.

Issues fixed/closed:

• Resolve part of https://github.com/nucypher/sprints/issues/150 (also check Investigate pure TS client-side implementation taco-web#635)

Notes for reviewers:

What should reviewers focus on?
Is there a particular commit/function/section of your PR that requires more attention from reviewers?

[fjarri]

This could be annotated with #[serde(with = "serde_bytes::as_hex")] similarly to bytestring fields in the main code, this way the test vectors will look a little tidier

[fjarri]

Also, just FYI, the umbral_pre::serde_bytes (that I wrote back in the day) has since been extracted into https://docs.rs/serde-encoded-bytes

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 56.25000% with 7 lines in your changes missing coverage. Please review.

Project coverage is 23.66%. Comparing base (5b531a4) to head (270cb58).

Files with missing lines	Patch %	Lines
nucypher-core/src/dkg.rs	56.25%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #102      +/-   ##
==========================================
+ Coverage   23.42%   23.66%   +0.23%     
==========================================
  Files          18       18              
  Lines        3475     3436      -39     
==========================================
- Hits          814      813       -1     
+ Misses       2661     2623      -38     

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