DEV: adds pointerup event to our select text helper (#1429)

This is needed for discourse/discourse#33143

Ideally we should move all these helpers to core, or improve the ones in core.

Author: jjaffeux

test/javascripts/acceptance/post-helper-menu-test.js

@@ -78,6 +78,8 @@ acceptance("AI Helper - Post Helper Menu", function (needs) {
     const selection = window.getSelection();
     selection.removeAllRanges();
     selection.addRange(range);
+    const event = new PointerEvent("pointerup");
+    document.dispatchEvent(event);
     await settled();
   }