Fix restore-agent timeouts

This patch parallels the previous one that fixed backup timeouts.
It establishes the same sort of state-machine process for walking
through the restore steps solely as events posted to the backup
manager's HandlerThread.

Fixes the rest of bug 5074923

Change-Id: I122a021cb1e9bb1342de0b71e5d4bc84cc630c58
1 file changed