Update MRTK3 to use latest XRI components

[AMollis]

This issue has been migrated a new MRTK repository, and the status of this issue will now be tracked at the following location:

• Update MRTK3 to use latest XRI components MixedRealityToolkit/MixedRealityToolkit-Unity#67

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Describe the problem

MRTK3 has implemented custom components on top of XRI that can now be replaced with XRI's latest feature set. We should update MRTK3 to take advantage of these new features and deprecate MRTK3's custom components.

The usage of these new components will be part of a new MRTK3 XR Rig. The existing MRTK rig may then be deprecated, in favor of using the new rig.

Tasks

• New MRTK3 XR Rig should utilize the XR Input Modality Manager for switching between controller and articulated hands. This would require XR Hands, and split MRTK3's ArticulatedHandController into two separate controllers, one for articulated hands and one for hand controllers. (MSFT Cost Estimate: 5)
• New MRTK3 XR Rig should utilize XR Interaction Groups. This may replace the need for MRTK3's IInteractionModeDetectors and Interaction Mode Manager. However, there still needs to be a way to disable hand rays if poking or grabbing something, so this may still require some form of the Interaction Mode Manager. Whatever is done, the Interaction Mode Manager can't interfere with the handling of UGUI like it does now (see MRTK3 NonNativeKeyboard & vanilla UGUI doesn't support near touch #11557). (MSFT Cost Estimate: 5)
• New MRTK3 XR Rig should utilize XR Poke Interactor. This would replace the need for MRTK3's PokeInteractor (MSFT Cost Estimate: 5)
• New MRTK3 XR Rig should utilize XR Gaze Interactor or be extended upon for eye gaze input. This may replace the need for MRTK3's FuzzyGazeInteractor. (MSFT Cost Estimate: 5)
• Usie XRI's teleporting rays (MSFT Cost Estimate: 3)