Stop future errors when encountering an async error

[davepagurek]

Resolves #7533

Changes:

• Introduces p5._error(), similar to p5._report, but that tries to stop all future errors from being logged
• Creates a static p5.isPreloadSupported() function: if preload is not supported, an error will be logged if the user includes a preload function. This always returns false, but compatibility addons can override this.

Screenshots of the change:

Live: https://editor.p5js.org/davepagurek/sketches/jUcmPEi8c (also try uncommenting the preload addon script tag!)

PR Checklist

• npm run lint passes
• Inline reference is included / updated
• Unit tests are included / updated

[davepagurek]

I also updated the preload addon to go along with these changes, it's included in the test sketch in the description and can be uncommented.

@ksen0 @limzykenneth I'm going to merge this in, and then I think we're good for another release. (Do we also want to publish the compatibility addons to npm as a beta release too?)