fix: flow and nested detections

[didroe]

Description

Fixes the following issues identified during testing:

• Ensure we descend down into unified nodes in Evaluator.TreeHas
• Replace Implementation.DescendIntoDetectionNode with Detector.NestedDetections - this logic existed to ensure object projections (ie. user.email) don't also detect the original object (ie. all properties on user in this case). This was previously done by avoiding descending into the receiver of a call when evaluating any detections. Instead we now define the object detectors as not allowing nested detections. ie. when a node returns a detection, we do not look for further detections in it's child nodes.

Checklist

• I've added test coverage that shows my fix or feature works as expected.
• I've updated or added documentation if required.
• I've included usage information in the description if CLI behavior was updated or added.
• PR title follows Conventional Commits format