Merge "Enable vendors to add preference controllers in mobile network...

Merge "Enable vendors to add preference controllers in mobile network settings" into udc-dev am: 89e829e3 am: 0e3ea95a

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Settings/+/23324419



Change-Id: I3463151328ed5ed16afb20616dd4f6e9653ac143
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>