Let the force field resolve the partial charge assignment

[jthorton]

Fixes #2116, #2117

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Checklist

• All new code is appropriately documented (user-facing code must have complete docstrings).
• Added a news entry, or the changes are not user-facing.
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[github-actions]

No API break detected ✅

View workflow run

Griffe output

$ griffe check "openfe" -s src --no-inspection --no-color --verbose -a origin/main

$ griffe check "openfecli" -s src --no-inspection --no-color --verbose -a origin/main

[jthorton]

If the user has 2.3.0 this will apply NAGL charges as the force field defines but might not be what the user wants if they expect am1bcc

[codecov]

Codecov Report

❌ Patch coverage is 25.00000% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.44%. Comparing base (1d4610b) to head (cd183a8).

Files with missing lines	Patch %	Lines
...openfe/protocols/openmm_utils/charge_generation.py	25.00%	9 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2152      +/-   ##
==========================================
- Coverage   95.14%   90.44%   -4.70%     
==========================================
  Files         213      213              
  Lines       20916    20927      +11     
==========================================
- Hits        19900    18927     -973     
- Misses       1016     2000     +984     

Flag	Coverage Δ
fast-tests	90.44% <25.00%> (?)
slow-tests	?

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