app: Add UIJ permissions and battery exemption helper

[kenway214]

Change-Id: I11f2b38936a1772d8338f675e04843903126414d

[kenway214]

on new source downloadmanager delegates foreground-visible downloads to jobscheduler as user-initiated jobs (uij / uidt).
because droidspaces was missing android.permission.RUN_USER_INITIATED_JOBS and FOREGROUND_SERVICE_DATA_SYNC in its androidmanifest.xml, jobscheduler treated the job as an unprivileged background job.when jobscheduler started downloadjobservice, params.getnetwork() returned null.
in realsystemfacade.java, getnetwork(params) returned params.getnetwork() directly with no fallback.
downloadthread.java then immediately threw stoprequestexception(status_waiting_for_network, "no network associated with requesting uid") and kept rescheduling the job in a loop (status 190), causing rootfs repo downloads to stay stuck at 0%.