SysUI changes for Provider Model

This CL contains the below major logic changes:
1. Only show QS/SB Icons for the current default network
2. Support the new "no internet" icons
3. Add a new callback "setConnectivityStatus"
4. Use WiFi scan results for network availability check

Bug: 176428921
Test: Unit Tests, Manual Tests

Change-Id: Ib5e95353205cad4e0bdbd57ef823044fcc54b10d