Revise layout for Wifi Setup in XLarge screen

- revise xml for new layout
- introduce padding View objects for resizing screen when
  software keyboard is shown.
- We now don't show the detailed status of Wi-Fi module anymore
  in SetupWizard flow (like "disconnected", "connecting", etc.)
- remove Forget button and relevant code.

Bug: 3347865
Change-Id: Ieab3246f06ee73af59e247b3f9f31c7570efc71f