s3-printing: pass lpq command to job_submit

s3-printing: pass lpq command to job_submit

Currently the generic print backend does not fill the printing backend
job identifier (sysjob) on submission of a new job. The sysjob
identifier is required to correctly map jobs in the printer queue to
corresponding spoolss print jobs.

Passing the lpq command to job_submit allows the generic print backend
to check the printer queue for the new job following submission. This
behaviour will come in a later commit.