Add vehicle hal.

- vehicle hal is used for supporting car specific features.
- Each property can be written (=set), read (=get), or subscribed.
- Each property has configuration informaiton to tell what that property
  is and how it can be accessed.
- also adding dummy hal implementation.

bug: 25183740

Change-Id: Ib1cc1c11540f156db73552f2a18a8efb361002af
10 files changed