Merge "Add RtmNetlinkPrefixMessage class to represent RTM_NEWPREFIX message." into main am: 7dd2525646

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/3039360

Change-Id: I70ead9b124281f4173d25bea61db06ecec345672
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>