Implement user manager AIDL.

This CL implements add/remove user and onPasswordChanged.
clearUID functionality, which is also part of this API will be added in
a separate upcoming CL.

Bug: 176123105
Test: TBD
Change-Id: I610441b0aac225740e09039958542dcf2f4fe0b6
diff --git a/keystore2/src/lib.rs b/keystore2/src/lib.rs
index f9554ea..445aef6 100644
--- a/keystore2/src/lib.rs
+++ b/keystore2/src/lib.rs
@@ -29,6 +29,7 @@
 pub mod remote_provisioning;
 pub mod security_level;
 pub mod service;
+pub mod user_manager;
 pub mod utils;
 
 mod async_task;