Add keyboard navigation for printer carousel

plugins/UM3NetworkPrinting/resources/qml/MonitorCarousel.qml

@@ -19,6 +19,10 @@ Item
     height: centerSection.height
     width: maximumWidth
     
+    // Enable keyboard navigation
+    Keys.onLeftPressed: navigateTo(currentIndex - 1)
+    Keys.onRightPressed: navigateTo(currentIndex + 1)
+
     Item
     {
         id: leftHint

plugins/UM3NetworkPrinting/resources/qml/MonitorStage.qml

@@ -25,6 +25,11 @@ Component
         }
         width: maximumWidth
         
+        // Enable keyboard navigation. NOTE: This is done here so that we can also potentially
+        // forward to the queue items in the future. (Deleting selected print job, etc.)
+        Keys.forwardTo: carousel
+        Component.onCompleted: forceActiveFocus()
+
         UM.I18nCatalog
         {
             id: catalog
@@ -59,7 +64,9 @@ Component
             }
             width: parent.width
             height: 264 * screenScaleFactor // TODO: Theme!
-            MonitorCarousel {}
+            MonitorCarousel {
+                id: carousel
+            }
         }
 
         MonitorQueue