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/permission.rs b/keystore2/src/permission.rs
index 7f63834..b1bb999 100644
--- a/keystore2/src/permission.rs
+++ b/keystore2/src/permission.rs
@@ -310,6 +310,8 @@
         ClearUID = 0x200,    selinux name: clear_uid;
         /// Checked when Credstore calls IKeystoreAuthorization to obtain auth tokens.
         GetAuthToken = 0x400,  selinux name: get_auth_token;
+        /// Checked when IKeystoreMaintenance::onDeviceOffBody is called.
+        ReportOffBody = 0x1000, selinux name: report_off_body;
     }
 );