Fix file editor & preview (#32706)

Fix a regression caused by jQuery removal (`renderPreviewPanelContent`)

And simplify the file editor, it doesn't need to be that complex. And
remove jQuery code.

web_src/js/vendor/jquery.are-you-sure.ts

@@ -196,6 +196,6 @@ export function initAreYouSure($) {
   };
 }
 
-export function applyAreYouSure(selector: string) {
-  $(selector).areYouSure();
+export function applyAreYouSure(selectorOrEl: string|Element|$, opts = {}) {
+  $(selectorOrEl).areYouSure(opts);
 }