Add telemetry messages to registry

One of Telemetry service's triggers' action is logging events to Redfish
log [1][2]. This change appends messages from DMTF schema [3] to
registry collection, so that they become available for Telemetry
service.

Tested:
- Telemetry subset present under /redfish/v1/Registries
- Telemetry registry details present under
/redfish/v1/Registries/Telemetry
- Telemetry messages present under
/redfish/v1/Registries/Telemetry/Telemetry
- Telemetry messages appear in event log
(/redfish/v1/Systems/<str>/LogServices/EventLog/Entries) after being
sent using phosphor-logging

[1] https://github.com/openbmc/docs/blob/master/designs/telemetry.md?plain=1#L423-L426
[2] https://github.com/openbmc/phosphor-dbus-interfaces/blob/master/yaml/xyz/openbmc_project/Telemetry/Trigger.interface.yaml#L61-L62
[3] https://redfish.dmtf.org/registries/Telemetry.1.0.0.json

Change-Id: Ic0b82c695fc7755394becd120c301b6056e3ce19
Signed-off-by: Michal Orzel <michalx.orzel@intel.com>
diff --git a/redfish-core/src/registries.cpp b/redfish-core/src/registries.cpp
index 8c8b36a..61b27b5 100644
--- a/redfish-core/src/registries.cpp
+++ b/redfish-core/src/registries.cpp
@@ -2,6 +2,7 @@
 
 #include "registries/base_message_registry.hpp"
 #include "registries/openbmc_message_registry.hpp"
+#include "registries/telemetry_message_registry.hpp"
 #include "str_utility.hpp"
 
 #include <algorithm>
@@ -52,6 +53,11 @@
         return getMessageFromRegistry(
             messageKey, std::span<const MessageEntry>(openbmc::registry));
     }
+    if (std::string(telemetry::header.registryPrefix) == registryName)
+    {
+        return getMessageFromRegistry(
+            messageKey, std::span<const MessageEntry>(telemetry::registry));
+    }
     return nullptr;
 }