multi_viz: Allow float waveform and pcm format

[thorwhalen]

Right now we are limited to the WAV format with int16 numerical format.
This restriction stops some people from using the components.

We would like to:

• allow different numerical formats (starting with floats/doubles)
• allow pcm format (where there is no header, and sample rate and width are specified by user)

We can do this:

• in python, by transforming the input before feeding to the JS component
• in JS (which will allow JS users to also have access to this flexibility