We only want to render the account link and login items in the header.
And we want only render the Multitenancy and Administrators sections in
the admin sidebar.
We include the administrators management so it's possible to give
permissions to other users to manage tenants.
In order to restrict access to other sections by typing the URL or
following a link, we're only enabling the rest of the routes when we
aren't in the multitenancy management mode.
The `use_helpers` method was added in ViewComponent 3.8.0, and it's
included by default in all components since version 3.11.0.
Note we sometimes delegated the `can?` method to the controller instead
of the helpers, for no particularly reason. We're unifying that code as
well.
This way it'll be easier to decide when they should be rendered.
In order to be consistent, we're using the `Layout` module for both
components; previously, the navigation partial was in the `shared`
folder while the footer partial was in the `layout` folder, which IMHO
didn't make much sense.
