Allow server-side copying and merging of AlchemicalNetworks

[ianmkenney]

closes #221

[codecov]

Codecov Report

❌ Patch coverage is 96.20253% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.75%. Comparing base (a575b6f) to head (9374b9b).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
alchemiscale/storage/statestore.py	96.20%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #433      +/-   ##
==========================================
+ Coverage   78.58%   78.75%   +0.16%     
==========================================
  Files          29       29              
  Lines        4735     4829      +94     
==========================================
+ Hits         3721     3803      +82     
- Misses       1014     1026      +12     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.