initial directory setup for CTS system app test

- Actual test should be added later.
- There are other work to be done to make this work.
  For now, this is just a placeholder.
- Added test can be run like normal android test, but it will not be
  added to CTS zip yet. But until dummy app is added there to system image,
  the APK should be pused to system/priv-app using adb push or adb sync.
- Build should be done with mmm as there is no Android.mk under tests/systemAppTest intentionally.
- The test should be complete by itself, and should not use external
  package for instrumentation (instrumentation should be only done to this
  package itself) as that external package may not have system permission.

bug: 10360298

Change-Id: I8f292c41738fab3830ff0c4ab99a47444a86d154