Merge "Listen for pref64 RA attributes in IpClientLinkObserver." into rvc-dev am: 1e420c1d39 am: e665b54a0e am: 00e451bfb2

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/modules/NetworkStack/+/11080388

Change-Id: I17ffb6d4a3be46f9d041071544d843e18ced44d3