Refactor: move registries functions to their file

There were same functions from namespace 'registries' in
event_service_manager.hpp. Move them to registries.cpp/hpp.

Tested:
- Using Redfish Event Listener, test subscriptions and eventing.
- Redfish Service Validator passes

Change-Id: Id0912f6581637bb4117e67b138122c355256b561
Signed-off-by: Alexander Hansen <alexander.hansen@9elements.com>
Signed-off-by: Ed Tanous <ed@tanous.net>
diff --git a/redfish-core/lib/event_service.hpp b/redfish-core/lib/event_service.hpp
index a75da35..d415496 100644
--- a/redfish-core/lib/event_service.hpp
+++ b/redfish-core/lib/event_service.hpp
@@ -20,8 +20,11 @@
 #include "http/utility.hpp"
 #include "logging.hpp"
 #include "query.hpp"
+#include "registries.hpp"
 #include "registries/privilege_registry.hpp"
+#include "registries_selector.hpp"
 #include "snmp_trap_event_clients.hpp"
+#include "utils/json_utils.hpp"
 
 #include <boost/beast/http/fields.hpp>
 #include <boost/system/error_code.hpp>