Refactors Cap and CapSet to New Design

[ryanmrichard]

PR Type

• [ ] Breaking change
• [x] Feature
• [ ] Patch

Brief Description

This PR creates "new" classes chemist::fragmenting::Cap and chemist::fragmenting::CapSet which are slightly reworked versions of the existing chemist::Cap and chemist::CapSet classes. In the process of refactoring the classes I also needed to extend NucleusView and PointChargeView to ensure that they could be created from Nucleus and PointCharge objects respectively.

Not In Scope

Any other refactoring called for from #369.

PR Checklist

• [x] Is documented
• [x] Is tested
• [x] Adheres to applicable organization standards

TODOs

• [x] Finish testing/documenting changes to PointChargeView
• [x] Finish testing/documenting changes to NucleusView
• [x] Finish testing Cap
• [x] Convert CapSet over
• [x] Test CapSet

[ryanmrichard]

This is r2g.