Enable the Processor to delete resources created when a job DELETE is submitted

[francescoingv]

If a Processor creates resources as an execution request, i.e. generating files (for the created job) to be returned by reference,
these resources are not visible to the Manager: possibly the Manager may know the reference (URL), but not the resource (full filename on filesystem).
When the API receive a DELETE for the job, then the resources (i.e. the above files) should be removed/deleted.

The only "entity" aware of the location of these resources is the Processor,
therefore the Processor should be able to receive a request to DELETE the generated resources.

The Manager should call a new method exposed by Processor while the Manager is processing a delete_job() request.

Describe the solution you'd like
Have a new, void method (hook) on BaseProcessor: say new_method(self, job_id: str)
This will cause no impact to current implementations not using this feature.

Have the BaseManager a new method to identify the Processor from the job_id, and call Processor.delete_job(): say new_method(self, job_id: str)
Modify the implemented Managers to invoke super.new_method(job_id) from within delete_job()

I would like to make it if approved.