conversation_module: add "created" to syncing

So that clients can show whenever a syncing conversation was added

Change-Id: Iccee12066384e0ccc78e3a96b8e5137b79bfa314

src/jamidht/conversation_module.cpp

@@ -1958,7 +1958,7 @@ ConversationModule::conversationInfos(const std::string& conversationId) const
             JAMI_ERROR("Conversation {:s} doesn't exist", conversationId);
             return {};
         }
-        return {{"syncing", "true"}};
+        return {{"syncing", "true"}, {"created", std::to_string(itConv->second.created)}};
     }
 
     return it->second->infos();

test/unitTest/conversation/conversation.cpp

@@ -2839,6 +2839,7 @@ ConversationTest::testSyncingWhileAccepting()
 
     auto convInfos = libjami::conversationInfos(bobId, convId);
     CPPUNIT_ASSERT(convInfos["syncing"] == "true");
+    CPPUNIT_ASSERT(convInfos.find("created") != convInfos.end());
 
     Manager::instance().sendRegister(aliceId, true); // This avoid to sync immediately
     CPPUNIT_ASSERT(cv.wait_for(lk, 30s, [&]() { return conversationReady; }));