Summary:
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.

Test Plan:
{F6804095}

{F6804094}

Reviewers: #plasma, #vdg, ngraham

Reviewed By: #vdg, ngraham

Subscribers: abetts, davidedmundson, plasma-devel

Tags: #plasma

Maniphest Tasks: T10586

Differential Revision: https://phabricator.kde.org/D20969