ve.ui.MWAdvancedSettingsPage: Convert page to use FieldLayout

This makes it look much more reasonable.

Before this the labels and controls where all inline blocks on one
continuos line wrapping half-way a button group.

Change-Id: I041b91654de9d899d5dce8942a187355bfac9b78
Merge "ve.ui.MWAdvancedSettingsPage: Convert page to use FieldLayout"