Add Support for Part Modifications

[rgauss]

Currently Control Part Modifications of Adds Alters are not being displayed in OCSCALProfile, more specifically OSCALControlModification. Parts may contain [0, 1] parts or [0, 1] props.

Current Behavior

When loading the Profile https://raw.githubusercontent.com/GSA/fedramp-automation/master/baselines/rev4/json/FedRAMP_rev4_MODERATE-baseline_profile.json, Control part RA-5.a says there are 2 modifications but only lists 1.

Expected Behavior

Parts are displayed. For the image below, it would be more valuable to show are the title and prose than the individual props

Helpful Resources

Outline of adds:

This has been discussed and attempted to fix at #53.

[rgauss]

Raised by @tuckerzp.