✅(oidc) add IdP e2e test for login

This is a simple test to assert a user can login via people when setup
as an identity provider.

src/frontend/apps/e2e/__tests__/app-desk/oidc-identity-provider.spec.ts

@@ -0,0 +1,30 @@
+import { expect, test } from '@playwright/test';
+
+test.describe('Login to people as Identity Provider', () => {
+  test('checks a user with mailbox can login via people', async ({ page }) => {
+    // go to people index page, wait for the redirection to keycloak
+    await page.goto('/');
+    await page.locator('h1').first().textContent({
+      timeout: 5000,
+    });
+
+    // keycloak - click on the login button
+    await page.click('a[id=social-oidc-people-local]');
+
+    // wait for the people login page to load and fill email/password
+    await page.fill('input.c__input[type="email"]', 'user-e2e@example.com');
+
+    await page.fill('input.c__input[type="password"]', 'password-user-e2e', {
+      timeout: 10000,
+    });
+
+    await page.click('button.c__button[type="submit"]');
+
+    // wait for URL to be localhost:3000 and the page to be loaded
+    await expect(page).toHaveURL('http://localhost:3000/', { timeout: 10000 });
+
+    // check the user is logged in
+    await expect(page.getByText('Groups')).toBeVisible();
+    await expect(page.getByText('0 group to display.')).toBeVisible();
+  });
+});