This allows the framework to ask for a monitor to use for backups that
are initiated by the framework (i.e. scheduled backups). Previously
the only way to pass a monitor in was through the
BackupManager#requestBackup API.
I also moved BackupManagerMonitorWrapper to a separate class now that
it's shared by three different classes.
Bug: 252763821
Test: atest CtsBackupHostTestCases
Also manually by implementing a simple monitor inside LocalTransport
and calling the new getBackupManagerMonitor.
Change-Id: I84d56a3e80d6c94f9a327f7d71876d1bc27fe5ac
f7fbe355ed