Add better logging for uncaught exceptions in DDLProc/DMLProc

DMLProc and DDLProc will both silently end if exceptions are caught in the initialisation phase and some other places in the execution. The following needs to be fixed:

• Exceptions at the end of ddlproc.cpp need to be logged
• Exceptions in DMLServer::start() need to be logged
• Need to check if there are other failure scenarios in these processes that are not logged