Parse RTM_NEWPREFIX netlink message in IpClientLinkObserver. am: 1c37811ffd am: 046242bd51

Original change: https://android-review.googlesource.com/c/platform/packages/modules/NetworkStack/+/3036733

Change-Id: Ic13308aea054094751fb1f1043c7aba7421f0b93
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>