Merge "cpp codegen redesign, unit test support" am: 99d4a49d am: 6f1c3fe8 am: 06aefcba

Original change: https://android-review.googlesource.com/c/platform/build/+/2642133



Change-Id: Ibc32b6ac8f7e4897545cdee7c6ddb9556bceaa1d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>