API/UI of partitioned job feature in aggregator

[soxofaan]

(from #52 )

Current "partitioned job" POC used non-standard "job_options" when submitting jobs to select tiling approach.
With other splitting approaches under investigation (#53, #54, #55), the question is how we standardize/document all the related tuning options: as "job_options", encoded in process graph in some way (output format option, special process, ...?)