Make pages settings (e.g. enablement access-control) more visible.

Summary

Part of the pages settings is located in the project settings(Settings -> General -> Visibility).

Access control is handled there and pages can be:

• disabled

  .

• enabled only for authorized users

  

Both of these states are not reflected on the pages settings page in any way:

This page sais that your site is available even if pages are disabled. And it tells nothing about access control.

Proposed solutions

Replace the whole page content with "Pages are disabled for this project" if pages are disabled

Something like: "Pages are disabled for this project. To enable it visit Settings->General->Visibility"

If access-control is enabled add a warning next to "It may take up to 30 minutes before the site is available after the first deployment."

From @marcia's comment:

Access Control is enabled for this Pages website; only authorized users
will be able access it. To make your website publicly available,
navigate to your project's **Settings > General > Visibility**
and _[do this]_. Read the [documentation](link-to-doc) for more information.

The link is project-url/edit#js-shared-permissions right now, but I'm not sure if this anchor will be present in the future, we'll probably need and integration test for that.

Screenshots of new behavior

cc @ogolowinski @mnichols1 @darbyfrey