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/Android.bp b/keystore2/Android.bp
index 0a5fb29..fec74f6 100644
--- a/keystore2/Android.bp
+++ b/keystore2/Android.bp
@@ -24,6 +24,7 @@
         "android.security.authorization-rust",
         "android.security.compat-rust",
         "android.security.remoteprovisioning-rust",
+        "android.security.usermanager-rust",
         "android.system.keystore2-V1-rust",
         "libanyhow",
         "libbinder_rs",
@@ -66,6 +67,7 @@
         "android.security.authorization-rust",
         "android.security.compat-rust",
         "android.security.remoteprovisioning-rust",
+        "android.security.usermanager-rust",
         "android.system.keystore2-V1-rust",
         "libandroid_logger",
         "libanyhow",