feat: register global + tone.js example

[b-ma]

Minimal example for Tone.js

Several open questions:

• should we include this register-global.js thing in the lib, looks like "yes" as it may really help to work with existing libs / frameworks, helpful to use faust (cf. faustwasm updated to 0.14.0. #164 (comment)) or wam plugins for example.
• cannot get rid of Tone.setContext(audioContext), somehow related to how standardized-audio-context works but couldn't find the reason

Maybe would be nice to work on the compatibility with standardized-audio-context first?