Fixes #8127: add errata counts to the content host details page.

Add errata counts to the content host details page and link to
the content host's errata page.

http://projects.theforeman.org/issues/8127
That is a `$stateParams` variable, see https://github.com/Katello/katello/pull/4778/files#diff-0040447a05db8287e71ad738fef4f2c1R29.