async load function

[quinton-ashley]

An async function simply named load could be used to load any file or multiple files asynchronously and return a promise.

This will be implemented in q5-util.js The q5 setup function is already async.

This idea was suggested by @mattdesl and iterated on by @mvicky2592 in this p5.js issue discussion. I also think keeping the preload system for backwards compatibility and ease of use for beginners is the right idea though.
processing/p5.js#6767

[quinton-ashley]

@DipakKhade Thanks for the PR! But please comment on an issue before trying to implement a feature though.

The implementation of load(...args) should use Promise.all. Also it should be able to load many types of files, not just text and json. It would need to be a function added to instances of Q5 not Q5 itself, in order to access other loading functions.

After examining the p5 feature request again more closely, I'm a bit confused myself about how they plan to support loading images, video, and sounds with this one method. I suppose it could wrap preload functions like loadImage and loadSound in a promise. What do you think of that idea?

I also think we need to figure out a way for addon developers to add support to q5 load for loading additional file types but that could be added after an initial implementation is done.