Explore using Prism's missing nodes to improve on type formatting accuracy

[vinistock]

Since YARP Prism can tell us which nodes are missing, we might be able to improve the accuracy of our on type formatting completions if we check which parts of a node are a MissingNode.

Let's explore if this makes the implementation simpler and more robust.

[st0012]

IRB already uses Prism to handle something similar (example). It could be a good reference for anyone wants to give this a try.