Added interactor list scrolling to MRTK3 (experimental)

[AMollis]

Overview

This adds an experimental method of scrolling through a Unity ScrollRect using XRI interactors. The sample scene demonstrates how to scroll through a canvas SrollRect using both the poke and hand ray interactors.

To accomplish this, the new experimental component InteractableEventRouter was added. The InteractableEventRouter component routes child XRI events to other child and parent game objects that contain the IXRInteractableEventRouteTarget component.

The following image shows a sample usage of this component. In this usage, the InteractableEventRouter is configured to bubble up select and hover events from child games objects.

Fixes

• MRTK3: Scrolling Views do not work with user input. #10736

Known Limitations

The InteractbleEventRouter currently can't handle IXRInteractableEventRouteTargets being dynamically added. So, this may limit some use cases, such as wanting to trickle down events to children added dynamically.

Verification

• Unit Tests in progress