Add intra-package job concurrency limits.

Add limits so that individual packages can't run more than X number
of jobs concurrently (so that we allow other apps to run their jobs
as well). For now, limit packages to 3 concurrent expedited jobs and
8 concurrent regular jobs. TOP apps are not subject to this restriction,
and the restriction also only comes into effect if there are more jobs
running+pending than slots available.

Bug: 171305774
Test: atest frameworks/base/services/tests/servicestests/src/com/android/server/job
Test: atest frameworks/base/services/tests/mockingservicestests/src/com/android/server/job
Test: atest CtsJobSchedulerTestCases
Change-Id: Id9d6f118b078ab54e3abafffd7d0ed00795d19c6