Merge "Disallow unknown fields in soong variables file" into main am: 4eef64a7

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/3114140



Change-Id: I79650c9d87247d91f9a33454a1ff7e3e3a7abeef
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>