Add Automotive OS API 29 stubs to platform SDK optionals. am: ecf644f2d6 am: 7737e3dc01 am: 683c5ffe37 am: 6edb7d4bfa am: 9e9c29a89e am: 8e679859ef

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

Change-Id: I3fb03c2488fd81daac073eea5f38047072435a12