Merge "Add feature flag for advanced vpn" into tm-qpr-dev am: e8a0ffc8

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/21957563



Change-Id: Ifa32d5aac38e88b7e813b34d3a11d80b285c672e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>