Merge "Report UnflaggedApi issues as warnings but treat as errors when new"...

Merge "Report UnflaggedApi issues as warnings but treat as errors when new" into main am: 5fa409b8

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/3248013



Change-Id: Ieeb57fcf4365e1134123f17a16a7ad8d6d5d6bcd
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>