libbinder_rs: Add libbinder_rs_on_trusty_mock

Build a mock version of Trusty libbinder_rs
on Android for build testing purposes.

Bug: 242243245
Test: m libbinder_rs_on_trusty_mock
Change-Id: I1b61550af6fbbeac68903c41b5bd20729973b066
diff --git a/libs/binder/tests/Android.bp b/libs/binder/tests/Android.bp
index 424ff84..35002eb 100644
--- a/libs/binder/tests/Android.bp
+++ b/libs/binder/tests/Android.bp
@@ -436,6 +436,7 @@
     required: [
         "libbinder_on_trusty_mock",
         "libbinder_ndk_on_trusty_mock",
+        "libbinder_rs_on_trusty_mock",
         "binderRpcTestService_on_trusty_mock",
         "binderRpcTest_on_trusty_mock",
     ],