libbinder: Add binderRpcTestService for Trusty

Add Trusty code and build files for binderRpcTestService
so we can run the binderRpcTest tests on Android against
a Trusty service.

Bug: 230135749
Test: build Trusty
Test: mmm tests
Change-Id: Id4dbe453229c1f1b93da2811cec265c0e331edfe