libbinder: Split universal tests from Android-specific

Add a new binderRpcUniversalTests.cpp that contains all
the tests that can be run on any OS, leaving the
Android/Linux-specific tests in binderRpcTest.cpp.
This allows other operating systems, like Trusty,
to compile binderRpcUniversalTests.cpp by itself and
ignore the other file.

Bug: 230135749
Test: mmm tests
Change-Id: I382ed03b0dc9df4123b231077dce456ac7f555ba