Copy WifiSettings base code into WifiSettings2 without WifiTracker

Copied main logic from WifiSettings into WifiSettings2, removing
all instances of WifiTracker in preparation of adding WifiTracker2.

Removed:
 - WifiDialog (to be added back in)
 - Context Menu (to be added back in)
 - Leftover SUW code (Next button)

WifiSettings2Test also copied directly from WifiSettingsTest, without
context menu test.

Bug: 70983952
Test: atest WifiSettings2Test

Change-Id: Ie1ef5bf0ca14f5989f4add2165422609f12c2c84