Connect reference context and target nodes

[handrews]

• For 3.0 Reference Objects, this means drawing the same edge that points from its parent to the Reference Object to the Reference Object's target
• For Path Item Objects and 3.1 Reference Objects, there can be merging behavior (overwrite of summary or description for 3.1 ROs, no-conflict merging for PIOs), so in some sense unless the merge behavior is not used, there needs to be a new merge result node, and the original nodes (particularly in the PIO case) need to be indicated as not used directly
• For Link Objects, operationRef and operationId behave more like a regular sub-object field that just happens to be done by reference. There probably just needs to be an operation edge that is present regardless of whether operationRef or operationId is used
• For other direct (mapping in the Discriminator Object) and indirect (Security Schemes, Tags, ...) referencing, it's a little less clear what is needed, and might vary based on the exact reference type