Add Automotive OS API 29 stubs to platform SDK optionals. am: ecf644f2d6 am: 7737e3dc01 am: 683c5ffe37 am: 6edb7d4bfa am: ce6e26c405

Original change: https://googleplex-android-review.googlesource.com/c/platform/development/+/12221485

Change-Id: Ia74e55ede6373ed63bc9bdceb16ed259ac41d7ad