Restructure app for scale and easy access of routeId

src/routes/courses/[id]/allexercises.svelte

@@ -0,0 +1,18 @@
+<script context="module">
+  export async function preload({ params }) {
+    let [courseId, courseNavItem, lessonId] = params.id;
+
+    return { courseId, courseNavItem, lessonId };
+  }
+</script>
+
+<script>
+  import PageNav from '../../../components/PageNav/index.svelte';
+  import CourseContainer from '../../../components/CourseContainer/index.svelte';
+
+  export let courseId;
+</script>
+
+<CourseContainer title="ReactJS" {courseId}>
+  <PageNav title="All Exercises" />
+</CourseContainer>