Experimentally Support Android Studio to build LatinIME

With this CL, you can build LatinIME and run tests for it on Android
Studio. This is still experimental and is not an official way to build
LatinIME though.

Bug: 110741422
Test: Made sure that you can build LatinIME with Android Studio
Change-Id: Ia75e3f74fa5f9b5f93dfac0b920c2e650aafa083