Wifi usability:  Add device mobility state into Wifi usability stats

Device mobility state is helpful for predicting Wifi usability in a
future time conditioned on current Wifi status.
Populate the device mobility state and the associated timing information
in WifiMetrics.

Bug: 129409568
Test: frameworks/opt/net/wifi/tests/wifitests/runtests.sh

Change-Id: I22139bd2cc753d79623f35dec791c82332261cd9
Signed-off-by: Mingguang Xu <mingguangxu@google.com>
2 files changed