Fixes #32841 - Host registration - :rhsm_base_url helper

[stejskalleos]

For theforeman/foreman#8563

[theforeman-bot]

Issues: #32841

[ekohl]

Oh, another complication: the RHSM port is 8443 on Pulp mirrors. I really think #9413 (which implements it as a function on the Smart Proxy) is better. For reference, the relevant bit:

      def rhsm_url
        # TODO: We shouldn't relate this to the Pulp feature and also expose it
        # as a setting
        if pulp_mirror?
          "https://#{URI.parse(url).host}:8443/rhsm"
        elsif pulp_primary?
          "https://#{URI.parse(url).host}/rhsm"
        end
      end

[jturel]

Left two comments on code style but testing in conjunction with the Foreman PR works well. Here's the resulting bits from my rhsm.conf:

hostname = centos7-katello-devel.jturel.example.com
prefix = /rhsm
port = 443
[rhsm]
# Content base URL:
baseurl = https://centos7-katello-devel.jturel.example.com/pulp/content

[jturel]

APJ

[jturel]

[test katello]