Terminate event handling after calling `Layer.handleLayerKeyEvent()`

There's no need to trigger a keyboard HID report after processing a layer
change, so stop processing before calling `prepareKeyboardReport()` if
`event.key` is a layer change `Key`.

Signed-off-by: Michael Richters <gedankenexperimenter@gmail.com>

src/kaleidoscope/Runtime.cpp

@@ -178,7 +178,7 @@ Runtime_::handleKeyEvent(KeyEvent event) {
   // If it's a built-in Layer key, we handle it here, and skip sending report(s)
   if (event.key.isLayerKey()) {
     Layer.handleLayerKeyEvent(event);
-    //return;
+    return;
   }
 
   // The System Control HID report contains only one keycode, and gets sent