fixes #6330 - using pulp & pulp_node features of smart proxy

* to determine the default smart proxy
* to determine whether to show the lifecycle env selection screen
* to determine which proxies to show under the content source selection on host(group) page

Depends on 
 * [ ] https://github.com/theforeman/smart-proxy-pulp/pull/1
 * [ ] https://github.com/Katello/puppet-capsule/pull/13
 * [ ] https://github.com/Katello/katello-installer/pull/95
Scratch this comment: I just looked over the rest of the refferencing PRs