Track which web request created a job

Track which web request created a job

We currently push a request id into structured logging (monolog/
logstash) to allow seeing all logs that were triggered by the same
request. This extends that to pass the id through jobs so jobs triggered
by a web request also share the same id and can be tracked together.
This web request id will follow jobs both directly created by a request,
and jobs created by those jobs.

This should give us some more visibility when debugging into what
started a particular job, and if a large number of jobs blowing up the
job queue are somehow related.

Change-Id: Iedbd031e6e9bb18fd6f7b923c8c305102255ab4b