Provide FlowLayout for Qt Quick

While there is a layout corresponding to most of the positioners, there is no FlowLayout.
Please consider implementing a FlowLayout.

One simple example use case that is not possible with the Flow positioner:

FlowLayout {
  id: flowLayout
  Item {
    id: item0
    Layout.fillWidth: true
    Layout.minimumWidth: 100
  }
  Item {
    id: item1
    Layout.minimumWidth: 100
  }
}

• If the flowLayout had width=150, then it would have two rows, with item0 with width=150 in the first row and item1 with width=100 in the second row.
• If the flowLayout had width=300, then it would have just one row with item0 with width=200 and item1 with width=100.