[FUI21.1] Create NetworkIdentityUtils class am: 178bc96fdd am: 5995a9f441

Original change: https://android-review.googlesource.com/c/platform/frameworks/libs/net/+/1566233

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I06516f6266cb01f00b3939fe89ca1169d53c8873