Add server flag support to flags. am: 96c315ea am: bae2e74f

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/20313762



Change-Id: I8463d62d2ba505457a98a9abde19a4840a078778
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>