Both execdb and task artifacts need a form of task UUID added to the command line options for the libtaskotron runner. Instead of continuing to use the -j for jobids, add a new --uuid flag that takes the new format of uuids, with the intention of retiring the existing -j later.

If no --uuid is given at execution time, generate a UID using the current UTC timestamp so that the local execution process can work well (identifiable UIDs, no need to connect to a full taskotron deployment etc.)