Allow vold to deleteAllKeys in Keystore

Add deleteAllKeys to IKeystoreMaintenance and allow vold to call it.
Allow vold to read the property
`ro.crypto.metadata_init_delete_all_keys.enabled`

Bug: 187105270
Test: booted twice on Cuttlefish
Ignore-AOSP-First: no merge path to this branch from AOSP.
Merged-In: I2fb0e94db9d35c1f19ca7acb2f541cfb13c23524
Change-Id: I2fb0e94db9d35c1f19ca7acb2f541cfb13c23524
6 files changed