Frontend.Maui: override application name to null in Gtk

And remove DBus slot from snapcraft.yaml. This disables DBus
functionality that was causing problems with snap package.

snap/local/snapcraft_maui.yaml

@@ -17,17 +17,10 @@ layout:
   /usr/lib/cli:
     symlink: $SNAP/usr/lib/cli
 
-slots:
-  dbus:
-    interface: dbus
-    bus: session
-    name: Microsoft.Maui.MauiGtkApplication.geewallet
-
 apps:
   geewallet:
     extensions: [gnome]
     command: bin/geewallet-maui-gtk.sh
-    slots: [ dbus ]
     plugs:
       - network
 

src/GWallet.Frontend.Maui/Platforms/Gtk/GtkApp.fs

@@ -8,5 +8,8 @@ open Microsoft.Maui.Hosting
 
 type GtkApp() = 
     inherit MauiGtkApplication()
+
+    // force Gtk to not use DBus
+    override _.ApplicationId = null
 
     override _.CreateMauiApp() = MauiProgram.CreateMauiApp()