Record events for RA option lifetimes

This patch defines a new android.net.metrics.RaEvent class carrying
lifetime values contained in RA packets. RaEvent are recorded when
ApfFilter processes a new RA for which there is no match.

Example:
ConnectivityMetricsEvent(15:39:39.808, 0, 0): RaEvent(lifetimes: router=3600s, prefix_valid=2592000s, prefix_preferred=604800s, route_info=-1s, dnssl=-1s, rdnss=3600s)

Change-Id: Ia28652e03ed442d5f2a686ef5b3fafbcb77c503a
3 files changed