Fix icon location on Wifi Settings

Wifi icons are showing up on the right of the name; which is unlike
other settings; this change fixes that.

Wifi settings are using standard preference layout; so moving to the
new location requires setting different property (icon instead of widget)
on the preference fragment.

Bug: 15117166
Change-Id: I5dd0a843139512d16fb70dd99ed12c3584f57895