👔(backend) add Organization model

We introduce the Organization model has a "hat" for all
users and team.

Each User must have a "default" organization.
Each Team must have an organization.

When a User creates a new Team, the team is linked to their
default Organization.

For now the Organization should not be visible to end users
this is a purely technical aspect as it.

The models are also adding a permission to allow User to edit
an Organization, but for now there are no endpoints for that.

Next steps:
- Add an Organization to each User and Team on all environments
  to mark Organization as mandatory in database.
- Add scope to Organization to list the Service Provider list
  allowed for a User in an Organization.
- Add endpoints + frontend to manage Organization's scopes

CHANGELOG.md

@@ -53,6 +53,7 @@ and this project adheres to
 - ✨(api) add RELEASE version on config endpoint #459
 - ✨(backend) manage roles on domain admin view
 - ✨(frontend) show version number in footer #369
+- 👔(backend) add Organization model
 
 ### Changed