Update HiPS URL and message handler setup

[Carifio24]

This PR is to address an issue discovered while trying to run CosmicDS in an environment with restrictive (i.e. HTTPS-only) internet. The issue is that we use an HTTP URL for the HiPS WTML, together with the fact that message handlers aren't properly set up if the collection load here fails.

This attempts to address the issue by:

• Having the HiPS URL protocol match that of the window - in particular, we'll use an HTTPS URL in an HTTPS context
• Moving the message handler setup into a finally block for the HiPS collection load. In the case that load fails, a query script that wants to set up HiPS catalogs won't be able to do so, but that was already going to be the case anyways.
  • Note that we aren't using a return value here, so there's no issue with moving this functionality from then -> finally.