[IMP] web: tests: show dialogs when debugging a test

By default, dialogs are hidden in tests, s.t. we don't see them
flicker when running the test suite. There is a css rule to hide
them, only if there's no "debug" classname on the body.

This commit toggles this classname when a test is run with
QUnit.debug.

closes odoo/odoo#84694

Signed-off-by: Mathieu Duckerts-Antoine <dam@odoo.com>

addons/web/static/tests/qunit.js

@@ -309,6 +309,7 @@
     });
 
     QUnit.debug = (name, cb) => {
+        document.body.classList.add("debug");
         QUnit.config.debug = true;
         QUnit.only(name, cb);
     };