Add charge generation provenance

[jthorton]

Is your feature request related to a problem? Please describe.
It would be great if we could add some form of provenance describing the charge generation method used via our charge API, this should be attached to the ligands fed through the functions. We had a go at this in a script which uses the charge API here. This results in a charge provenance sd tag on each ligand of the form

>  <charge_provenance>  (1) 
{"openfe_version": "1.8.0", "openff_toolkit_version": "0.18.0", "rdkit_version": "2025.09.4", "charge_method": "am1bccelf10", "oeomega": "20251120", "oequacpac": "2111"}

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