Revert "Revert "Add utilities to create IPv6 ICMP messages."" am: 5bb30ebaef

Original change: https://android-review.googlesource.com/c/platform/frameworks/libs/net/+/1611913

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Iebd5118edc045cb23a9b194fdd15288dd5f867e1