Fixed cors error for image editor

refs https://github.com/TryGhost/Team/issues/3034

- while fetching the image from source for editing in the image editor, it throws cors error when the image is returned from cache instead of ghost server
- the cached image response causes cors to trip over if admin url is different from frontend url for site as it doesn't has the right header
- adds a dynamic `v=...` query param while fetching image in editor to bypass cache and fetch image from server directly

ghost/admin/app/components/koenig-image-editor.js

@@ -113,8 +113,9 @@ export default class KoenigImageEditor extends Component {
     @action
     async handleClick() {
         if (window.pintura) {
+            const imageSrc = `${this.args.imageSrc}?v=${Date.now()}`;
             const editor = window.pintura.openDefaultEditor({
-                src: this.args.imageSrc,
+                src: imageSrc,
                 util: 'crop',
                 utils: [
                     'crop',