Link Probing: collect metrics

Collect link probe metrics in aggregated form as histograms.
Created a reusable histogram class with ranged buckets.

Bug: 112029045
Test: frameworks/opt/net/wifi/tests/wifitests/runtests.sh
Change-Id: Ieb30050a5803d2ff7564d9a1bb599f2ef9dc2efa
9 files changed