ConnectivityController tracks jobs by UID.

There could be hundreds of jobs requesting connectivity. A single
ArraySet for all of them is inefficient. Splitting by UID makes
processing a little bit faster.
This should also help make job quota management easier.

Bug: 117841374
Bug: 111423978
Bug: 117846754
Test: atest com.android.server.job.controllers.ConnectivityControllerTest
Change-Id: I8b3b0209c6b57c91b13a69106b6fe8705b26d385