METRICS: histograms of scanresult sums in scan

Generate histograms counting the size of 5 different ScanResults
subsets within a scan. Subsets include: total, open,
saved, open-or-saved, or passpoint related scan results. The size is
counted for unique BSSIDs & unique SSIDS, generating two histograms.

This metric is useful for determining the frequency of N-way
network-selection decisions (where N is the number of connectable
networks).

Exempt-From-Owner-Approval: Prior approval by owners (rpius)
Bug: 36819798
Test: Added unit test
frameworks/opt/net/wifi/tests/wifitests/runtests.sh

Change-Id: I4825a778d45f9306f3e83b2418a047b8809c1802
6 files changed