Refs #969 - Proxy-side changes for serving templates from the proxy

An update to @GregSutcliffe's original PR. Ports his original feature to the new
plugin api.
Fixes #8160 - Remove chef related code

Code was extracted to separate chef plugin. See
https://github.com/theforeman/smart_proxy_chef
fixes #8300 - set webmock custom HTTP status response correctly
Fixes #8320 - shutdown shell provider threading fixed
Refs #8267 - pass template_url in call to foreman

Also passes the ?static parameter on correctly
fixes #8278 - update foreman-prepare-realm for freeipa 4
Fixes #8347 - facts feature should not be enabled by default
fixes #7197 - add man page for foreman-prepare-realm