[BUGFIX] ckeditor: propagate changes in editor document

If the document model in a ckeditor instance is changed, the changes are
now immediately written back to the related source element and a
`change` event is dispatched, recovering the modal window when closing
the FormEngine.

Resolves: #98717
Releases: main
Change-Id: If605018a2c11e6448900639b2b8fd0fa5d0f4c2b
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/78322
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Stefan Bürk <stefan@buerk.tech>

Build/Sources/TypeScript/rte_ckeditor/ckeditor5.ts

@@ -132,10 +132,14 @@ export class CKEditor5Element extends LitElement {
 
         CKEditor5
           .create(this.target, config)
-          .then((editor: EditorWithUI) => {
+          .then((editor: CKEditor5) => {
             this.applyEditableElementStyles(editor);
             this.handleWordCountPlugin(editor);
             this.applyReadOnly(editor);
+            editor.model.document.on('change:data', (): void => {
+              editor.updateSourceElement();
+              this.target.dispatchEvent(new Event('change', { bubbles: true, cancelable: true }));
+            });
 
             if (this.options.debug) {
               window.CKEditorInspector.attach(editor, { isCollapsed: true });