a11y: Improve tab order for "Appeareance" settings
requested to merge michaelweghorn/ktexteditor:michaelweghorn/a11y_improve_tab_order_appearance_settings into master
Align the tab order (i.e. the order in which widgets receive focus when moving through the dialog using the Tab key) with the visual order of the widgets in the "General" -> "Appearance" settings page, so the focus doesn't unexpectedly "jump" around.
To achieve that, move the widgets from row 2 of the layout above those from row 3 in the .ui file as well, so they are constructed earlier. And drop the manually specified tab order that was just including two widgets.
This way, the widgets are constructed in the same order as their visual order, and tabbing through the page follows that order.
An alternative would be to manually specify the tab order for all widgets manually, s. https://doc.qt.io/qt-6/designer-tab-order.html .