Merge branch 'add-user' into 'master'

backend/.env.example

backend/package-lock.json

frontend/.env.development

frontend/src/assets/placeholder.jpeg

frontend/src/components/BurgerMenu.vue

frontend/src/components/Footer.vue

frontend/src/components/SearchBar.vue

frontend/src/router/index.js

frontend/src/views/AddUsers.vue

frontend/src/views/Connexion.vue

frontend/src/views/Home.vue

frontend/src/views/Users.vue