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: I430d856014a226ef345bd2349f0601062dcaa8c7