Update MRTK3 buttons and interactables to gracefully handle Spatializer Plugins that require an audio mixer

[marlenaklein-msft]

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 buttons and interactables to gracefully handle Spatializer Plugins that require an audio mixer MixedRealityToolkit/MixedRealityToolkit-Unity#181

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Overview

The Microsoft Spatializer requires that audio sources have a spatialized audio mixer applied to the OutputAudioMixerGroup field. MRTK3 should create a mechanism to automatically configure its interactable's audio source, so to support the project's spatializer plugin.

The solution might be a warning with, Fix It button. Or a component that you add to the scene to automatically patches interable's audio sources. Or a pre-build step that patches scene's audio sources before building.

Whatever the solution is, it should be to opt-in, since not all applications will require spatialization.