Rename second CustomBondForce in HybridTopologyFactory system and update docstrings

[zhang-ivy]

Description

• Renames second CustomBondForce in HybridTopologyFactory system to CustomBondForce_exceptions
• Updates docstring in HybridTopologyFactory to contain the list of forces present in the hybrid system
• Fixes docstring for RESTTopologyFactory to accurately reflect the forces in the system

Motivation and context

This change is necessary because #1007 changes compute_potential_components() to use a dictionary where the keys are force names and values are energies.

How has this been tested?

Change log

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 52.27%. Comparing base (66ab558) to head (37828f7).
Report is 79 commits behind head on main.

Additional details and impacted files

[ijpulidos]

We also need to change the validate_endstate_energies_point because I changed it assuming the bonded forces wouldn't have different names and now it is just broken because we now not only have different names but also different number of components, as far as I can see.

@zhang-ivy I can contribute code fixing this part once the other parts are completed.

[ijpulidos]

It also makes me realize that we need more testing for this part, because tests should've failed with the previous PR (#1007 ), so we might want to deal with #1011 at the same time.

[ijpulidos]

We also need to change the validate_endstate_energies_point because I changed it assuming the bonded forces wouldn't have different names and now it is just broken because we now not only have different names but also different number of components, as far as I can see.

@zhang-ivy from our discussion, thanks for pointing out my confusion, we don't need to change that function, but we might think of better ways of accomplishing what it does without hardcoding forces/components names. Hopefully we can come up with an easy and more robust way, if not, then it's not too bad to leave it as it is.

[mikemhenry]

@ijpulidos I think this will fix https://github.com/choderalab/perses/runs/6547307832?check_suite_focus=true right?

[zhang-ivy]

@mikemhenry : I don't think this PR will fix that failure, as this PR modifies the HybridTopologyFactory, whereas the failure you pointed out comes from a test for the RESTCapableHybridTopologyFactory

[zhang-ivy]

@mikemhenry : Also, I think the test failure you linked above is old -- the gpu tests are currently passing.

[mikemhenry]

Just one suggestion!

[mikemhenry]

LGTM

[ijpulidos]

Looks good!