signpost layout
The signpost layout is a very specialised layout.
It does not provide a content area because the content follows a very specific format.
Instead, the layout accepts a trio of variables:
title,
hooks,
and secondaryHooks.
The hooks variable is required in order for the layout to make sense.
The other two are optional and will not block rendering.
It extends from the task layout, so all masthead blocks are still available.