Fixes #36940 - Add SecureBoot support for arbitrary operating systems…

… to "Grub2 UEFI" PXE loaders

In the course of theforeman/foreman#9864 and theforeman/smart-proxy#877,
SecureBoot support for arbitrary operating systems has been added to the
"Grub2 UEFI" PXE loaders.
This patch adds a new parameter 'bootloader_universe' to the TFTP
configuration and a directory 'host_config' inside the TFTP root
directory, that are both required by the aforementioned PRs.

manifests/tftp.pp

@@ -13,7 +13,7 @@
     root => $root,
   }
 
-  $dirs = pick($directories, prefix(['pxelinux.cfg','grub','grub2','boot','ztp.cfg','poap.cfg'], "${tftp::root}/"))
+  $dirs = pick($directories, prefix(['pxelinux.cfg','grub','grub2','boot','ztp.cfg','poap.cfg', 'host-config', 'bootloader-universe/pxegrub2'], "${tftp::root}/"))
 
   file { $dirs:
     ensure    => directory,