status/network: Set default name for toggle title

Following the previous commits where we left the quick toggle title
open for the new title scheme, set the titles for all network pills
to what currently is the "default" name.

That means, we pull the device name from Network Manager for devices,
through the disambiguate function, and hardcode 'VPN' for VPN
connections.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2619>

js/ui/status/network.js

@@ -1318,6 +1318,10 @@ const NMToggle = GObject.registerClass({
         this._itemBinding = new GObject.BindingGroup();
         this._itemBinding.bind('icon-name',
             this, 'icon-name', GObject.BindingFlags.DEFAULT);
+        this._itemBinding.bind_property_full('source',
+            this, 'title', GObject.BindingFlags.DEFAULT,
+            () => [true, this._getDefaultName()],
+            null);
         this._itemBinding.bind_full('name',
             this, 'subtitle', GObject.BindingFlags.DEFAULT,
             (bind, source) => [true, this._transformSubtitle(source)],