Add APIs to log B&R events during delayed restore

Add methods to BackupManager to allow system apps to acquire
BackupRestoreEventLogger and upload logs after a restore operation for
their package had already finished.

Move UserBackupManagerServiceTest under 'mockingservicetests' target and
add testReportDelayedRestoreResult_sendsLogsToMonitor that mocks a
static method.

Bug: 260687705
Test: atest UserBackupManagerServiceTest
Change-Id: Ia873efe27847e0b2a489ef083a36fc001e6167c3