Add CLI flag to pass job-id to puppet agent

In order to actually thread job-id from orchestrator through the agent to PuppetDB, we need to have a facility to provide the job-id to the agent. As of PUP-7149, the code exists internally in puppet to handle job-id, but there's no way to pass it in from the outside. That ticket was contingent on a refactor of the way pxp-agent interfaces with puppet to start using the API instead of the command line. That work is deferred due to complexity, so the revised solution is to just provide a flag to set job-id on the command line.