Add missing javascript dependencies to package.json. Move javascripts files to app/javascript. Add first javascript test. Change test mode

app/javascript/dashboard.js

@@ -0,0 +1,14 @@
+export function initializeListenersForNavDropdowns(){
+  document.addEventListener("turbolinks:load", function() {
+    const schoolDropdown = document.querySelector('#select-school');
+    if (schoolDropdown) {
+      document.querySelector('#select-school').addEventListener('change', (event) => {
+        window.location = event.target.value;
+      });
+
+      document.querySelector('#select-district').addEventListener('change', (event) => {
+        window.location = event.target.value;
+      });
+    }
+  });
+}