npl: npls more conveniently instantiable

NPLs can now be instantiated using brace-init lists, as well as by passing
any iterator-capable container.

refs: #4345

Change-Id: Ib43373d5899d0ac14861027c34431fa928eec191
diff --git a/tests/test-statistics.cpp b/tests/test-statistics.cpp
index bc029e1..b148cb2 100644
--- a/tests/test-statistics.cpp
+++ b/tests/test-statistics.cpp
@@ -248,8 +248,7 @@
                                    Statistics::PacketType::SENT_ADJ_LSA_DATA);
 
   // Name LSA
-  NamePrefixList prefixes;
-  prefixes.insert("/ndn/name");
+  NamePrefixList prefixes{ndn::Name{"/ndn/name"}};
 
   NameLsa nameLsa(routerName, seqNo, MAX_TIME, prefixes);
   lsdb.installNameLsa(nameLsa);