VM: Introduce writePayloadRpData/readPayloadRpData

VM payload require an api to allow storing n bytes' data with
confidentialty & tamper evidence integrity guarantees.

Microdroid Manager implements this using the vm_secret module, which
uses the payload's DICE chain to store/get secret from Secretkeeper.

Additionally introduce a test that uses these api.
Test: #rollbackProtectedDataOfPayload
Bug: 378911776

Change-Id: Id39f5c6c626531029bf33ef5d28dc237881e40e6
diff --git a/tests/testapk/src/native/testbinary.rs b/tests/testapk/src/native/testbinary.rs
index e479342..2b2fa28 100644
--- a/tests/testapk/src/native/testbinary.rs
+++ b/tests/testapk/src/native/testbinary.rs
@@ -132,6 +132,12 @@
     fn readLineFromConsole(&self) -> BinderResult<String> {
         unimplemented()
     }
+    fn insecurelyReadPayloadRpData(&self) -> BinderResult<[u8; 32]> {
+        unimplemented()
+    }
+    fn insecurelyWritePayloadRpData(&self, _: &[u8; 32]) -> BinderResult<()> {
+        unimplemented()
+    }
 }
 
 fn unimplemented<T>() -> BinderResult<T> {