🎨(frontend) add dsfr proconnect homepage

If we are with the DSFR theme, we need to add the
proconnect button to the homepage.
We add an option in the cunningham theme to
display the proconnect section instead of the
opensource section.

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

@@ -1,6 +1,6 @@
 import { expect, test } from '@playwright/test';
 
-import { keyCloakSignIn } from './common';
+import { expectLoginPage, keyCloakSignIn } from './common';
 
 test.describe('Header', () => {
   test.beforeEach(async ({ page }) => {
@@ -98,6 +98,6 @@ test.describe('Header: Log out', () => {
       })
       .click();
 
-    await expect(page.getByRole('button', { name: 'Sign in' })).toBeVisible();
+    await expectLoginPage(page);
   });
 });