Add option to only show apps in the current workspace in the running apps widget

niri only currently - but should be simple enough to add support for
others

Services/CompositorService.qml

@@ -70,6 +70,15 @@ Singleton {
         detectCompositor()
     }
 
+    // return only the toplevels on the current workspace on the given screen
+    function filterCurrentWorkspace(toplevels, screen){
+	    if (useNiriSorting) {
+		    return NiriService.filterCurrentWorkspace(toplevels, screen)
+	    }
+	    //fallback to returning everything
+	    return toplevels
+    }
+
     function detectCompositor() {
         // Check for Hyprland first
         if (hyprlandSignature && hyprlandSignature.length > 0) {
@@ -119,4 +128,4 @@ Singleton {
         }
         Hyprland.dispatch("exit")
     }
-}
+}