Convenient way extract components from `ChemicalSystem`

[ijpulidos]

In the current implemented protocols that use gufe objects for alchemiscale, we find that we need ways to extract components from the ChemicalSystem. For example as in https://github.com/OpenFreeEnergy/openfe/blob/2af8dcda2921ccfa131456bb291453ca3c487dbb/openfe/protocols/openmm_utils/system_validation.py#L139

This raises the question of whether this utility function/method should be part of the ChemicalSystem object itself. It seems like a good candidate of a commonly used functionality that gufe could provide, and if the inner structure of how the ChemicalSystem object changes protocols don't have to keep track and adapt when this happens.

I think it could be desirable to have something like chemical_system.get_components(type=SomeComponentType). I'm raising this question here for further discussion.

[richardjgowers]

@ijpulidos yeah having ChemicalSystem.get_components_of_type(type: Component) -> list[Component] would work fine. Since the ChemicalSystem is just a dict[str, Component all this method would do is [c for c in cs.components.values() if isinstance(c, type)] but I guess it's a handy.

[ijpulidos]

Yes, I think it could be something that gufe could provide, and the complexity shouldn't be that hard, there might be a need to make some logic to make sure we are not returning a component more than once. I think since these are GufeTokenizable we should be able to use set operations for this, correct?

[dotsdl]

Possibly related to #144! Thanks @ijpulidos!