[WIP] Add AlchemicalArchive

[ianmkenney]

This PR introduced the AlchemicalArchive for serializing an AlchemicalNetwork along with it's transformation results. Closes #323.

[codecov]

Codecov Report

❌ Patch coverage is 97.72727% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 98.75%. Comparing base (5c281ff) to head (91c4a02).

Files with missing lines	Patch %	Lines
gufe/archival.py	97.72%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #687      +/-   ##
==========================================
- Coverage   98.76%   98.75%   -0.02%     
==========================================
  Files          40       41       +1     
  Lines        2517     2561      +44     
==========================================
+ Hits         2486     2529      +43     
- Misses         31       32       +1     

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[github-actions]

No API break detected ✅