ByteStreamCnvSvc+ByteStreamCnvSvcBase+TrigByteStreamCnvSvc: Enable thread-safety checking.

Enable thread-safety checking. Fix resulting warnings. Rework ByteStreamCnvSvc to manage slot-specific copies of event data.

Remove the RawEvent pointer from ByteStreamCnvSvcBase; moving it to ByteStreamCnvSvc as part of thread-safety work. ByteStreamCnvSvcBase then becomes an abstract class, so remove it from the entries file.