Merge "[FUI20] Expose UnderlyingNetworkInfo as system Api" am: 75b50a5c73

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1563496

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Icbc3c9f8e1ac8064e2e006587b4d4870d74cee2d