Support two pane design in the Settings app.

1. Only enable this feature when the flag is on and library is supported
in this device.
2. Add a placeholder rule for home menu.
Network page will be shown to the right pane by default.
3. Add a rule for most sub settings pages.

Known issues:
1. Transition animation seems wrong in this cl.
2. App is closed if user taps back key on the second layer page in fold
state.

Test: Run the apk on large screen device and regular phone. No crash
happens
Bug: 197716926

Change-Id: I089717e84c5e92c6e5b02d9770a24376e250fea2