Image2 could have limiter for resizing image to specified maximum

[jswiderski]

Type of report

Feature request

Provide description of the new feature

Originally reported here: https://dev.ckeditor.com/ticket/12701

Image2 could have an extra setting or field in dialog for defining maximum resize size. If doing that inside the dialog, we could have a checkbox (Limit resizer to current image size) or 2 fields for entering max width/height manually. We could also have a configuration option with predefined values e.g. image_size, image_size+20, 200x300.

[mlewand]

It make sense to put it as a config option.

Rather than string format with <width>x<height> it should accept an object, like:

{
	width: 400,
	height: 300
}

There should be one special case, if you pass values as strings:

{
	width: 'naturalWidth',
	height: 'naturalHeight'
}

It will retain proper values from img.naturalHeight / width.

There's no need for supporting mixing something like 'naturalWidth+20' if ever anyone will need that kind of stuff we'd make a callback for it. But I don't think there's a need for that.