Explicitly call setCursor in the QQuickMouseArea constructor

QQuickItemPrivate has a boolean hasCursor that is used by QQuickWindow
to determine whether to use the cursor for an item. QQuickMouseArea has
a default cursorShape of Qt.ArrowCursor that is ignored due to hasCursor
not being set. Thus, call setCursor in the QQuickMouseArea constructor
to sync the cursor state of the QQuickItem and the MouseArea.

Task-number: QTBUG-33157