JobQueue: Create a debugging queue

JobQueue: Create a debugging queue

As a part of creating the kafka-based JobQueue implementation,
we need to transition to the new queue smoothly and be able to
first debug the event production side, then try executing a no-op
job in parallel with each of the real jobs (to be able to check
deduplication and all the jpb management code) and only then
try switching jobs one-by-one to the new backend queue.

In order to achieve that at first we need to temporary produce
both to the old job pipeline and to the new one - thus creating
a queue 'splitter' - it delegates all the methods to the main
queue while the produce requests also go to the EventBus.

This class it temporary, so it's marked deprecated right away.
It will not be needed once the queue transition is over.

Bug: T163380
Change-Id: I483b8f00f1c593ff3af6ba6826868b553339525f