Keystore 2.0: Implement onDeviceOffBody.

Add onDeviceOffBody to KeystoreMaintenance interface.

Also rename user_namanger.rs to maintenance.rs.

Bug: 171305684
Test: N/A
Change-Id: I382213533c3891084159cefce8c32b4fe69e91bc
diff --git a/keystore2/src/lib.rs b/keystore2/src/lib.rs
index 2e8ced6..cb47e3e 100644
--- a/keystore2/src/lib.rs
+++ b/keystore2/src/lib.rs
@@ -27,13 +27,13 @@
 pub mod key_parameter;
 pub mod legacy_blob;
 pub mod legacy_migrator;
+pub mod maintenance;
 pub mod operation;
 pub mod permission;
 pub mod remote_provisioning;
 pub mod security_level;
 pub mod service;
 pub mod shared_secret_negotiation;
-pub mod user_manager;
 pub mod utils;
 
 mod attestation_key_utils;