Initial submit of Vehicle HAL 2.1

Major changes / decisions:

- created empty IVehicle@2.1 interface to distinguish HAL impls
  from client's (Car Service) perspective;
- created default 2.1 implementation that currently delegates all
  calls to existing 2.0 implementation
- had to refactor a little bit 2.0 thus components could be esily
  imported in 2.1

TOOD:
- move OBD and VMS code to 2.1
- decouple "DefaultVehicleHal.cpp"
- rename "DefaultVehicleHal" to Emulator (let's call things by their names)

b/34716856

Test: todo

Change-Id: Ib23650ca1277f0dfb24e5c789d65a19dce8b1abc
diff --git a/automotive/Android.bp b/automotive/Android.bp
index aa8f74f..0302cd5 100644
--- a/automotive/Android.bp
+++ b/automotive/Android.bp
@@ -2,4 +2,5 @@
 subdirs = [
     "vehicle",
     "vehicle/2.0",
+    "vehicle/2.1",
 ]