[FUI21.1] Create NetworkIdentityUtils class am: 178bc96fdd am: 5995a9f441 am: db190ae790

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

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Ib199b071e7ae52cab30268f32a00e8e61db616f1