Restructure page components, add canonical links

tests/testcafe/404.test.ts

@@ -0,0 +1,17 @@
+/**
+ * TestCafé test fixtures.
+ * This file is used by TestCafé to run end-to-end tests with chrome against the site.
+ * Tests are grouped into fixtures and fixtures into files.
+ */
+import { Selector } from "testcafe";
+
+fixture`404 page renders and functions correctly`.page("http://localhost:3000/404");
+
+test("Page contains the text 404", async t => {
+  /**
+   * Test if there is a favicon element on the page
+   */
+  const elem = Selector(".not-found-page");
+  await t.expect(elem.textContent).contains("404");
+});
+