Make generator "resumable"

[JohnStrunk]

The workload generator is intended to be run as a Deployment (in the cluster under test). In order to recover from disruptions, the generator should be able to "pick up where it left off" if it is restarted.

For the purposes of this item, the goal is to be able to locate and adopt the existing workloads from a previous run. In practice, this means finding them in the assigned namespace and creating a Lifecycle event for each of them.