cmd/mbf: jstest: implement DSL and runner

cmd/mbf/internal/pkgserver/ui/jstest/index.html

@@ -24,7 +24,11 @@
 <div id="root">
 </div>
 
-<script type="module" src="./jstest.js"></script>
+<script type="module">
+    import "../all_tests.js";
+    import { DOMReporter, GLOBAL_REGISTRAR } from "./jstest.js";
+    GLOBAL_REGISTRAR.run(new DOMReporter());
+</script>
 </main>
 </body>
 </html>