Dialog: Simplify contentItem to fix implicitHeight not being passed up
For some reason, the contentItem ColumnLayout was not updating its implicitHeight to the scrollview's implicitHeight, causing dialogs to sometimes open with 0 height on the first open (subsequent opens have the correct height).
We actually can simplify this by using the ScrollView directly rather than wrapping it inside a ColumnLayout, which avoids the need to pass implicitHeight upwards.
This issue is reproducible in dialogs that use repeaters to load content: