Create default page for non-opted in s3proxy users

[Jose-Matsuda]

Related to: #1538 (comment)

Need default virtualservice for the "Storage" button on the kubeflow interface.

There needs to be a "404" page for users who have not opted in to s3proxy rather than a blanc "no route found" message from kubeflow.

Jose Questions

1. Where will the 404 page be? Will we add a page to central dashboard and then the VS reroutes it to that on failure?
2. I suppose we add user documentation for what the Storage button is for

Mathis Question

Do we even want to show the user the storage option if they're not in it?

Result

After discussing during technical elaboration, we will first hide the storage option from the menu items. In the future, we will implement a proper page to display when users haven't opted-in to s3proxy.

[mathis-marcotte]

After looking into it, just temporarily removing the link would probably be more work than just already implementing the default page. So the ticket will revert to its original goal.

[mathis-marcotte]

When looking into this, there didn't seem to be a need for a virtual service to accomplish this. In the central dashboard code, there was already logic in place to determine if an iframe failed to load. So, it was just a matter of appending on to that so that if it failed while trying to get s3 proxy, itwould just redirect to the newly created default s3 proxy page instead of the generic "no page found" error page.

While testing, I had two namespaces: "mathis-marcotte" which had s3proxy and "mathis-test" which did not have s3 proxy. When clicking on the "storage" link with my first namespace, we can see that it can access the s3proxy explorer through the iframe.

When trying to access it with my second namespace, we can see that it does not have access and the default page is displayed(the page is very basic for now with just a message that is a bit more detailed compared to the "page not found" message).

[mathis-marcotte]

Merged with the solution mentioned above.