- port from QQC1 to QQC2
- replace ColumnLayout with Kirigami.FormLayout
- make use of twinFormLayouts
NOTE: On initial loading I get a blank providers comobobox,This patch replaces the `ColumnLayout` with `Kirigami.FormLayout` and make use of `twinFormLayouts` to link child layout with parent layout.
QQC1 comboboxes are retained due to a QQC2 bug with resizing the popup to delegate width. but after selecting an option it's OK.