Add two new document type layouts

The Value list document has two columns for keys and values, and the left column for keys is much bigger than the right column for values. The widths of these columns come from the two column layout that is one of the default document type layouts.

To make the left column much smaller than the right one (switch the widths of 30% and 70%) we need a new layout.

How to make a new layout is documented:

https://documentation.bloomreach.com/library/concepts/document-types/custom-editor-layout.html

Why don't we provide this layout by default?