Move online error codes from TrigKernel to TrigSteeringEvent
Move the online error codes from the exclusively-online HLT domain to the Trigger domain which is also part of offline releases. This is done in order to facilitate reading online error codes in offline monitoring and analysis, as required e.g. by !30261 (merged).
Two major changes are made:
- The class name is changed and the definition moved to TrigSteeringEvent, with all clients adapted.
- The HLTResultMT interface is changed to use the codes explicitly as they are now available and defined in the same package.