HostController.find_by_name needs refactoring
Presently this method makes unnecessary checks for permissions (which could be handled by scope) and restricts itself to Host::Managed which can break Discovery. This should also be refactored to allow additional ways of finding a host.
Fixes #2644 - Refactor Host find_by_name to use several ways to find a
host, and refactor my_hosts scope to Host::Base, allowing us to remove
unnecessary permissions check from find_by_name