Broadcast the progress of Jobs

Instead of using the per process monitor, create a new global one. This
to collate all job progress into one broadcast.

Also add tests for job progress. Do it in this CL, as the CL introducing
functions to get progress will get optimized out as the code wasn't
used.

Bug: 385841586
Test: atest -c 'DocumentsUIGoogleTests:com.android.documentsui.services'
Flag: com.android.documentsui.flags.visual_signals_ro

Change-Id: Ib0df69a303dbe8bf3ebd0c337491dc48fef0b87f