[dnm] modifications needed restoring runs and showing compound SMILES

[jandom]

A bunch of related changes that I needed to do for resuming to work.

Discussed with @dotsdl – this is just a sketch "hey here is what I needed to do"

• don't break when directory structure already already exists (when resuming)
• add tests that confirm gufe doesn't break (doesn't actually test the resuming logic, that's vendor – specifically openmmtools)
• make sure the API payloads return smiles, useful for GUIs consuming the results

Things breaking right now

• easy, update tests to show that smiles is the expected output
• hard, the tests depend on openfe, which is not otherwise a dep of this package

Checklist

• Added a news entry – @jandom what's a news entry?

Developers certificate of origin

• I certify that this contribution is covered by the MIT License here and the Developer Certificate of Origin at https://developercertificate.org/.

[github-actions]

No API break detected ✅