Add build ICMPv6 echo request packet helper function in Ipv6Utils. am: 657b2e8660 am: 21839bcbdd am: 445f742223

Original change: https://android-review.googlesource.com/c/platform/frameworks/libs/net/+/1669829

Change-Id: I0280292a346f36c6a937c392fb82980b4ddf7741
tree: a3d09ab1a32fac9b32988bf7ca8f610d82213c15
  1. staticlibs/