`href` in caption editable not updating when using DrupalLink

Test only patch, should fail. It demonstrates the bug.

Interestingly, the change is present if you view the editable caption this way:

var editor = CKEDITOR.instances['edit-body-0-value'];
var figcaption = editor.widgets.getByElement(editor.editable().findOne('figcaption'));
console.log(figcaption.editables.caption.$.outerHTML);

But if you press the source button, it doesn't show.

Also, if you hit the "Save" button and check the output on the saved host node, it doesn't show the change.

If you put a print statement in captionEditableMutationObserver, you'll see it's not called when the link is edited with the drupalink dialog.

It works if you set attributes to true in the mutation observer:

-            var config = {characterData: true, attributes: false, childList: true, subtree: true};
+            var config = {characterData: true, attributes: true, childList: true, subtree: true};

Is that going to break something else? What was the rationale behind setting that to false?

Fantastic, thanks!