List of input smiles as input for `RelativeFEPSetup`

[ijpulidos]

Description

This changes the RelativeFEPSetup to accept a list of smiles as input.

It does it by trying to read the input parameter as smiles using the openff.toolkit.Molecule object and if it fails with a specific exception it assumes it is then a list of path to sdf/mol2 files.

Motivation and context

Resolves #1155

How has this been tested?

Test is failing with the following error

E       AssertionError: the difference between the atoms_with_positions_reduced_potential and the sum of atoms_with_positions_reduced_potential_components is nan

../rjmc/geometry.py:493: AssertionError

I think there is some information getting mixed up or lost when we do the trip from openff.toolkit.Molecule to OEMol using the .to_openeye() method from openff.

Change log