Convert TimelineDelegate to cpp

There are 2 main reason for doing this:
1. Because I can, I wanted to see if I could do it
2. It gets rid of the janky qml re parenting stuff so should be faster.

src/qml/HoverActions.qml

@@ -44,7 +44,7 @@ QQC2.Control {
     leftPadding: 0
     rightPadding: 0
 
-    x: delegate ? delegate.contentX + delegate.bubbleX : 0
+    x: delegate ? delegate.contentItem.x + delegate.bubbleX : 0
     y: delegate ? delegate.mapToItem(parent, 0, 0).y + delegate.bubbleY - height + Kirigami.Units.smallSpacing : 0
     width: delegate ? delegate.bubbleWidth : Kirigami.Units.gridUnit * 4