Wrapping lone list item in `list_item_scope` is annoying

[abey79]

ListItem are sometime used as a single item in isolation, eg to emulate a button or a title (e.g. component_path_button_to or the blue titles in the selection panel). In such instance, it's a bit annoying to have to wrap it a in list_item_scope. Maybe there could be some helper like ListItem::lone(id_source) (with a better name) to auto-wrap it in the scope.

[abey79]

• list_item_scope should be implemented using UiStack
• list items should behave properly "by default", aka "top-level" containers (windows/tooltip/etc.) should be "auto-scoped"
• explicit list item scope should be needed when fine-tuning is needed

For the last point, I see two cases:

• very long UI split in sections (e.g. selection panel): you dont want to force all property content to globally align
• do not force nested properties to align with parent properties (in some case it looks better that way)

For these, it is ok to have an explicit scope.