Boy this was hard.
To ease the pain of porting wireless-security to GTK4, add
a new WsFileChooserButton class that mimics the behavior of
a button that triggers a filechooser, as per the migration
guide suggests.
There were lots of GtkGrids, so the diff is particularly
horrendous. Sorry.
This needs serious testing before landing.
This means NetObject is now obsolete and can be removed.
There was a GtkSizeGroup that the mobile settings used, but it isn't clear if
this is still relevant. It should be added back later if found to be (this code
is likely to be removed to make way for a dedicated mobile panel).
In bug 689638, the designers only asked for the list icons
to be symbolic, not the big icons in the page headings. The
current code was failing on both ends: virtual devices like
vlan still had non-symbolic icons in the list, and several
pages (e.g mobile and proxy) had symbolic icons in the headings.
https://bugzilla.gnome.org/show_bug.cgi?id=693001
