feat: ensure /etc/NetworkManager/conf.d exists (#354)

- required to create dns-none setting

Reviewed-on: #354

modules/networking/manifests/init.pp

@@ -74,6 +74,12 @@ class networking (
   }
 
   # prevent DNS from being overwritten by networkmanager
+  file {'/etc/NetworkManager/conf.d':
+    ensure => directory,
+    owner  => 'root',
+    group  => 'root',
+  }
+
   if $networking::params::nwmgr_dns_none {
     file {'/etc/NetworkManager/conf.d/dns_none.conf':
       ensure  => 'file',