Change button text for commenting and closing an issue at the same time (#23135)

Close  #10468

Without SimpleMDE/EasyMDE, using Simple Textarea, the button text could
be changed when content changes.

After introducing SimpleMDE/EasyMDE, there is no code for updating the
button text.

web_src/js/features/comp/EasyMDE.js

@@ -77,6 +77,9 @@ export async function createCommentEasyMDE(textarea, easyMDEOptions = {}) {
 
   const inputField = easyMDE.codemirror.getInputField();
 
+  easyMDE.codemirror.on('change', (...args) => {
+    easyMDEOptions?.onChange(...args);
+  });
   easyMDE.codemirror.setOption('extraKeys', {
     'Cmd-Enter': codeMirrorQuickSubmit,
     'Ctrl-Enter': codeMirrorQuickSubmit,