Add deleteAllKeys to IKeystoreMaintenance

Add a method to IKeystoreMaintenance which calls deleteAllKeys on every
KM instance. This method will be called by vold when it detects a
factory reset.

Bug: 187105270
Test: booted Cuttlefish twice
Change-Id: Id23f25c69a74a99bfebbf28429651d6fd647dbcd
3 files changed