Force update wifi QS when opening.

This changes expands on ag/2608526 by forcing a refresh of AccessPoints
when the QuickSettings picker is opened. This consolidates logic between
QS and Settings, where in WifiSettings we forceUpdate on cold start.

Bug: b/62680006
Test: 1. Open the quick settings picker
2. Minimize the picker
3. Walk out of range of the networks you say listed in the picker
4. Re-open picker
5. Stale networks should not be shown, latest scan results should be.

Change-Id: Ia944dd3dbeff7d9c3774f04129c07f1ffd4466b2