Add image blur

[seekuehe]

Adds support for blurring images, including an effect to extend the blur beyond the original bounds of the image

There are two blur props applied, one to the image itself in <a:blip> and optionally under <p:spPr> for the bounding shape of the image.

Example

let pptx = new PptxGenJS();
let slide = pptx.addSlide();

slide.addImage({
  x: 1,
  y: 2,
  path: "https://images.unsplash.com/photo-1506744038136-46273834b3fb?crop=entropy&cs=tinysrgb&fit=max&fm=jpg&ixid=MnwyMTIyMnwwfDF8c2VhcmNofDJ8fGxhbmRzY2FwZXxlbnwwfHx8fDE2NTg5MzE0MDM&ixlib=rb-1.2.1&q=80&w=1080",
    blur: {radius: 20}
});

slide.addImage({
  x: 3,
  y: 2,
  path: "https://images.unsplash.com/photo-1506744038136-46273834b3fb?crop=entropy&cs=tinysrgb&fit=max&fm=jpg&ixid=MnwyMTIyMnwwfDF8c2VhcmNofDJ8fGxhbmRzY2FwZXxlbnwwfHx8fDE2NTg5MzE0MDM&ixlib=rb-1.2.1&q=80&w=1080",
    blur: {radius: 20, grow: true}
});

pptx.writeFile({ fileName: 'PptxGenJS-Blur.pptx' });

[pastafari]

So if I understand correctly, we apply blur to both <blip> and <effectLst> correct?

[seekuehe]

For the grow effect, yes

[pastafari]

Tested on sandbox locally. LGTM! 🎉