Pass caller information in cancelBugreport.

In preparation for a broader set of apps using BugreportManager, we
enforce that only the app which started a bugreport is allowed to cancel
it.

Bug: 161393541
Test: atest BugreportManagerTestCases
Test: manual with two apps triggering/cancelling BRs
Change-Id: I10bdc9ff2a5746e2dc1e7d63876219bb34fad3b9