fix(coremedia-richtext): Adapt to breaking API change

The system test _Should correctly render broken image with empty src_ fails.

This is (most likely) due to the breaking API change of
`setXLinkDataSetEntries`. To grant the old behavior, adding
`allowEmpty = true` to the call.

Author: mmichaelis

packages/ckeditor5-coremedia-richtext/src/rules/ImageElements.ts

@@ -56,7 +56,7 @@ export const imageElements: RuleConfig = {
       if (isHTMLImageElement(node)) {
         // title: Not mapping xlink:title to title yet, as we use the title
         // for generating tooltips regarding the related content.
-        setXLinkDataSetEntries(node, extractXLinkAttributes(node));
+        setXLinkDataSetEntries(node, extractXLinkAttributes(node), true);
         node.src = INLINE_IMG;
       }
       return node;