components/calendar: avoid creating (42+12+12)*3 MouseArea in MonthView
Before this each DayDelegate had one MouseArea, which is unnecessary since DayDelegate itself is a PC3.AbstractButton. The wheel event is handled in WheelHandler in SwipeView in MonthView.
- 42: 42 days
- 12: 12 months
- 12: 12 years
- 3: Previous, Current, Next
BUG: 470071 FIXED-IN: 6.0
Edited by Fushan Wen