Reduce logging level on non-OFE management API user errors

A number of methods in OperationContext and similar places throw runtime exceptions when error conditions are detected that are really due to user mistakes (e.g. trying to add a resource that's already present.) These are caught and logged at ERROR. It would be better if OperationFailedException were thrown, since those are only logged at DEBUG – logging client request errors at ERROR in the server log is noisy and will anger admins.

Unfortunately, OFE is a checked exception, so we can't throw it without making an incompatible API change that may break subsystems.

Solution is to create an OperationFailedRuntimeException and throw that. The logic that catches and handles OFE will do the same thing for OFRE.