Image JS Cross-Origin

[ReDrUm]

Recently changes to ImageLoader added a crossOrigin property to generated ImageElements in JS target HTML (e.g. when used by mui.display.Image).

It's currently on by default and you're able to opt out by adding a compilation flag to your project:

-D default_cross_origin

Many third party image hosts/services don't yet support this and you're forced to add the flag to your project otherwise loading their images are blocked. Additionally if your app is loading images off multiple third party servers it's possible that some may need the crossOrigin property set while others won't.

I propose we change it to be opt-in instead of opt-out, and also set it at the class level instead of globally.

[dpeek]

This was made opt-in so as not to break backward compatibility (someone actually submitted this change as a pull request, so I guess someone is using it at least...)

We'll need to do a major version bump to make the change.