[SB Refactor] Add tracking for wifi enabled state and pipe it through to

the UI.

Bug: 238425913
Test: manual: Turn on airplane mode and verify wifi icon disappears
(airplane mode => wifiEnabled = false)
Test: manual: Turn off airplane mode and verify icon reappears
Test: statusbar.pipeline tests

Change-Id: Idee192ffc6a26a180f2ff04213ffd3fd8a2f0ee4