✅(e2e) adapt tests to impress app

Adapt e2e test to works with Impress.

src/frontend/apps/e2e/__tests__/app-impress/404.spec.ts

@@ -0,0 +1,29 @@
+import { expect, test } from '@playwright/test';
+
+import { keyCloakSignIn } from './common';
+
+test.beforeEach(async ({ page, browserName }) => {
+  await page.goto('/');
+  await keyCloakSignIn(page, browserName);
+  await page.goto('unknown-page404');
+});
+
+test.describe('404', () => {
+  test('Checks all the elements are visible', async ({ page }) => {
+    await expect(page.getByLabel('Image 404')).toBeVisible();
+    await expect(page.getByText('Ouch')).toBeVisible();
+    await expect(
+      page.getByText(
+        'It seems that the page you are looking for does not exist or cannot be displayed correctly.',
+      ),
+    ).toBeVisible();
+    await expect(page.getByText('Back to home page')).toBeVisible();
+  });
+
+  test('checks go back to home page redirects to home page', async ({
+    page,
+  }) => {
+    await page.getByText('Back to home page').click();
+    await expect(page).toHaveURL('/');
+  });
+});