Sample Scene: Add InputActionsExample to MRTK3

[AMollis]

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

• Sample Scene: Add InputActionsExample to MRTK3 MixedRealityToolkit/MixedRealityToolkit-Unity#140

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MRTK2 Scene Name

InputActionsExample

Overview

This scene shows how to map inputs from different sources to a user defined input action and handle it via a single listener

Additional Context

• InputActionHandler removed in MRTK3
• Sample should demonstrate similar behavior using XRI

[AMollis]

Cutting this sample.