Demo of MicrophoneFeed with shader showing the captured waveform in stereo

[goatchurchprime]

This replaces #1172 that had added the shader on the old MicRecord demo (now removed to avoid any maintenance issues).

This demo example won't work without PR#108773 Add MicrophoneFeed with direct access to the microphone input buffer

That PR creates a MicrophoneServer which can make a MicrophoneFeed that can draw audio data directly from the microphone buffer without being tied to the clock timing of the audio system.

[AThousandShips]

Please apply suggestions as a batch (using the "add suggestion to batch") to avoid lots of changes

[goatchurchprime]

Please apply suggestions as a batch (using the "add suggestion to batch") to avoid lots of changes

Sorry, not an expert with this stuff. Thanks for the suggestions.