Fix right-clicking delegates again

I accidentally broke this while trying to dance around the two new
overlapping TapHandlers, but this didn't work. What ended up happening
is that you couldn't right-click non-message delegates anymore (such as
images, files, etc.)

I *still* couldn't figure out how to get overlapping TapHandlers to
work, so I just switched to a MouseArea instead. This makes everything
work as expected now.

src/timeline/MessageDelegate.qml

@@ -148,8 +148,8 @@ MessageDelegateBase {
         showBackground: root.cardBackground && !NeoChatConfig.compactLayout
 
         TapHandler {
+            acceptedDevices: PointerDevice.Mouse | PointerDevice.TouchPad | PointerDevice.Stylus
             acceptedButtons: Qt.RightButton
-            gesturePolicy: TapHandler.ReleaseWithinBounds
             onTapped: _private.showMessageMenu()
         }