Extend Foreman Facets to Allow Adding Included Attributes

Hello Semion,

I'd like to contribute to the Foreman Facet API so it can be used to add
included ActiveRecord attributes. This change is motivated by this comment
on a Katello pull request
<https://github.com/Katello/katello/pull/6236/files#diff-243193e44ff7150915ec447e89b4e205R24>
.

That pull request is trying to add content_view, lifecycle_environment,
etc. to the host object that is passed to the view to avoid N+1 query
warnings and increase performance of that page. I was told by Ori that you
would be a good person to ask for ideas on how to implement this change in
Foreman. Any help is greatly appreciated.

Regards,

Andrew Kofink
akofink@redhat.com
Associate Software Engineer
Red Hat Satellite