Add .lumi directly to database instead of doing it it first
After creating a new design, we can't add it directly to the database as an admin user: we have to download the .lumi file and upload it in the admin panel after that. For one design, it's ok, but when you created +200.. it's a nightmare.
So, as an admin, it's relevant to add a new design directly from the frontend with parameters like:
- category (undefined by default)