localhost should be served via SSL

[amitaibu]

We should be serving https://localhost:8000/ instead of http://localhost:8000/

One use case is that my Service worker doesn't work on Firefox, unless it is served via SSL.

This doesn't seem to work, though:

devenv.shells.default = {
    # Generate certificates for HTTPS localhost development
    certificates = [ "localhost" "127.0.0.1" "localhost:8000" ];

Different, but related, maybe worth also considering serving from a project-specific URL (e.g. https://my-project.ihp.site:4443/). Not sure how complex that would be.