More work on issue #26390151: Add new JobScheduler API...

...for monitoring content providers

We now have some delays before reporting URI changes, to allow
them to batch together.

Also clean up debug output, and fix some issues with how we
were managing the content observer state.

And while I am here, fix the device idle and app idle controllers
to no longer maintain their own list of jobs, but just directly
iterate over the JobStore.

Change-Id: If3fdff23c00c2f1b99901a9be096d851562d3439