handle propagation disablement - add DBMS_SCHEDULER.CREATE_JOB for dbms_aqadm.schedule_propagation

[paulparkinson]

[paulparkinson]

Propagation between pdbs can become disabled if a PDB is moved for maintenance, etc. This most commonly occurs if the user has setup the workshop and then returns to it after a number of days. We need to handle this by adding a DBMS_SCHEDULER.CREATE_JOB for dbms_aqadm.schedule_propagation (or some other way)