feat: add option to skipi image creation (#504)

Looks good to me - simply change to allow skipping the image creation.

src/imageLoader/createImage.js

@@ -150,6 +150,12 @@ function createImage(imageId, pixelData, transferSyntax, options = {}) {
   return new Promise((resolve, reject) => {
     // eslint-disable-next-line complexity
     decodePromise.then(function (imageFrame) {
+      // if it is desired to skip creating image, return the imageFrame
+      // after the decode. This might be useful for some applications
+      // that only need the decoded pixel data and not the image object
+      if (options.skipCreateImage) {
+        return resolve(imageFrame);
+      }
       // If we have a target buffer that was written to in the
       // Decode task, point the image to it here.
       // We can't have done it within the thread incase it was a SharedArrayBuffer.