Some new api endpoints require to send JSON data in HTTP requests but it was currently
not handled by the apidoc module.
So handle corresponding httpdomain directives in our custom rst nodes visitor.
Also add support for documenting JSON array of non object type as httpdomain does
not offer any directive for that type.
And yes I know the code in that module is awful but until we start implementing API v2,
we are stucked with it to display the HTML documentation.
Depends on D2665