Add layout listing to layout area

On layout area, there is no way to select a doctype/workflow/page provider to have a list of layouts, with context actions.

Having only access to layouts (on tree leafs) does not present easy solutions for context actions and info.

Specs

• Types/Workflow/page provider items are clickable
• They open a page with:
  • List of layouts (similar UI as in UI listings)
    • Each item as Configure or Edit / Revert actions
    • each of this listings should have its own URL

• Some listing might have below an area with binding elements (not in scope, just fyi)
• Below may also be the an area for help info (not in scope, just fyi)