MT#61052 support rendering yaml

some templates need to produce yaml output
(ie. copy entire portions of config.yml), which
supported with this change, ie.

  [% Utils.to_yaml(element_from_configyml) %]

there is libtemplate-plugin-yaml-perl, which is
avoided to not (re-) introduce deps other than
YAML::XS.

Change-Id: Iec7f9dd6d13270d9afa78fbe126f0e41d21b6ed7

lib/NGCP/Template/Plugin/Utils.pm

@@ -8,6 +8,7 @@ use parent qw(Template::Plugin);
 use MIME::Base64 ();
 use Data::Dumper ();
 use Config::General ();
+use YAML::XS ();
 
 sub new {
     my ($class, $context, @params) = @_;
@@ -37,6 +38,11 @@ sub to_config_general {
     return $conf->save_string($params[0]);
 }
 
+sub to_yaml {
+    my ($self, @params) = @_;
+    return YAML::XS::Dump($params[0]);
+}
+
 sub get_ref {
     my ($self, @params) = @_;
     return ref $params[0];
@@ -94,6 +100,10 @@ Serializes the given input object to string (perl syntax).
 
 Serializes the given input object to string (Config::General syntax).
 
+=item [% serialized = Utils.to_yaml(object) %]
+
+Serializes the given input object to string (YAML syntax).
+
 =item [% Utils.get_ref(object) %]
 
 Get the variable type.