Prepare the automatic testing integration

[Tirodem]

To consider :

• unit testing
• integration testing

To prepare :

• integration of a gherkin based nodeJS e2e framework (ex : Cypress)
• add test-id on CTA & dynamic labels on DOM pages
• manage test-ids under a test/prod toggle on /admin/config

[coyotte508]

Let's use vitest as the framework to add tests, it can also perform end to end tests

• add test-id on CTA & dynamic labels on DOM pages
• manage test-ids under a test/prod toggle on /admin/config

Let's talk more about this if needed