add JsonEncoder support role

lib/DU/Role/JsonEncoder.pm

@@ -0,0 +1,19 @@
+package DU::Role::JsonEncoder;
+
+use Moo::Role;
+
+use JSON::XS ();
+
+has _json_encoder => (
+   is => 'ro',
+   lazy => 1,
+   builder => '_build_json_encoder',
+   handles => {
+      encode_json => 'encode',
+      decode_json => 'decode',
+   },
+);
+
+sub _build_json_encoder { JSON::XS->new }
+
+1;