List members of a group

requires backend#535 (closed)
To do once #460 (closed) is finished.
A page should allow to list members of a group at route /group/<uuid>/. It will later be used to edit members privilege level and add new members.\

In the right module, we should store the paginated results of the current page only for a group. It should be loaded for each new page using Paginator component.

membersPage: {
    count: 42,
    number: 1,
    results: [
      {
        id: "user_1",
        email: "user_1@test",
        level: 70,
        […]
      }
    ]
  }
}