Complete PolicyRequestProcessor implementation

* Capture all screenshots regardless of policy match
* Apply attribution to all screenshots (top component)
* Pass default component (systemUI) into the processor
* Rename policy.apply to check, return PolicyResult
* Replace use of numActivities, vs. childTaskIds.size (bug)
* Better report on what is happening for triage/bug report

Bug: 327613051
Bug: 330329080
Test: TODO
Flag: ACONFIG com.android.systemui.screenshot_private_profile DISABLED
Change-Id: I7c7bd296bb71d9dc40df70758e21527436c2983d