Description of problem:

Assume we have an Upstream HTTP Server that is serving the extracted CDN ISO  content and a Downstream Server that can only talk to that http server.

We need to be able specify custom ca cert (or ca credential) when we change the RedHat CDN url to the upstream url.

Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
1. Get a content iso extracted in /var/www/html/pub/<myrepo> on some other box
2. Go to Subscriptions => Manage Manifest 
3. Change the redhat cdn url to  https://<fqdn>/pub/<myrepo>. Notice that you cannot specify the cert in this tab.
4. Go to Redhat Repositories and try expanding the available repositories.

Actual results:

You should get an error along the lines of 
2022-07-28T18:01:33 [I|app|37e3cb19] CDN: Requesting path https://<webserver>:443/pub/repos/content/dist/rhel/server/7/listing
/opt/rh/rh-ruby27/root/usr/share/ruby/net/protocol.rb:44: warning: exception in verify_callback is ignored
2022-07-28T18:01:33 [E|app|37e3cb19] Failed at scanning for repository: SSL_connect returned=1 errno=0 state=error: certificate verify failed (self signed certificate in certificate chain)


Expected results:

Ability to set the SSL CA Credential even for Red Hat CDN.


Additional notes:
https://github.com/Katello/katello/blob/master/app/lib/katello/resources/cdn.rb#L64 needs to have a logic along the lines of

if cdn_configuration.ssl_ca?
  options[:ssl_ca_cert] = cdn_configuration.ssl_ca  
else
  options[:ssl_ca_file] =  self.ca_file
end

We also need to be able to set a SSL CA Credential on the Manage Manifests.