Show information about prefabs in debugger

If an object has been created from a prefab, include some useful prefab context in the debugger - link back to original asset, nested prefab hierarchy, etc. Check out the methods in `PrefabUtility`.

Start by reviewing the methods in Unity's PrefabUtility and the existing debugger integration. Determine how to expose the original prefab asset and nested prefab hierarchy for objects created from prefabs; done means the debugger shows useful prefab context for those objects.

Written by the indexing model from the issue text.