[UX] Update home page and left menu

[RachL]

Description The home page currently looks like this:

URL : http://185.25.192.252:8080/ui/#/x-home

Main tasks:

• [x] Get rid of the "HOME" text
• [x] Change the welcome text to the following:

_Bienvenue sur votre catalogue commun !

Afin de visualiser vos produits, veuillez cliquer sur le bouton ci-dessous afin d'accéder à la page d'import :_

• [x] Text color should be black for now

• [x] Main button is centered but not main text

• [x] Main button redirects to the import page for now

• [x] Left menu is in capital letters, text in white background in grey rgb (102,102,102) (#666666)

Acceptance Tests

1. Log in as a user
2. Land on the home page and see changes as described above

Mockups