Waveform library design

[TenghuiZhang]

This is the PR to create waveform UI library based on the analysis node. It requires the ID of canvas element where the waveform will be rendered as initialization input. When the waveform is created, it requires the analyserNode as real-time audio input data for calculating the correct amplitude for waveform.

[TenghuiZhang]

This is the UI screenshot for waveform

[TenghuiZhang]

This is the waveform UI recording Waveform recording.webm

[TenghuiZhang]

This is the UI recording of waveform Waveform.webm

[TenghuiZhang]

All of the comments in SPN and worklet recording app.js are not the newest update version. The newest version is in the VUMeter PR: #337.