trusty-aidl: Add tests for AIDL code generation.

Adds test client and server that utilize AIDL-generated cpp backend.
Asserts that client-server communication is sound.

Test: trusty/vendor/google/aosp/scripts/build.py qemu-generic-arm64-test-debug --test "boot-test:com.android.trusty.binder.test"
Bug: 224644083
Change-Id: I7acee236101c3f8ef9fca06d9bb609a2a11cf14b
8 files changed