puppet: Move prod-static creation from voyager.pp to app_frontend.pp.

Every app frontend will need this directory and this should help
enable more modular puppet rules.

puppet/zulip/manifests/app_frontend.pp

@@ -132,6 +132,11 @@ class zulip::app_frontend {
     owner  => 'zulip',
     group  => 'zulip',
   }
+  file { '/home/zulip/prod-static':
+    ensure => 'directory',
+    owner  => 'zulip',
+    group  => 'zulip',
+  }
   file { '/home/zulip/deployments':
     ensure => 'directory',
     owner  => 'zulip',

puppet/zulip/manifests/voyager.pp

@@ -30,12 +30,6 @@ class zulip::voyager {
     notify => Service["nginx"],
   }
 
-  file { '/home/zulip/prod-static':
-    ensure => 'directory',
-    owner  => 'zulip',
-    group  => 'zulip',
-  }
-
   file { "/etc/cron.d/restart-zulip":
     ensure => file,
     owner  => "root",