Walder support for queries for layouts

[renevds]

Certain layouts require date from a query, currently the only way to make this work is by adding the necessary query to every view that uses this layout.

Perhaps a system could be implemented where when rendering with a layout, Walder will check if a query has been defined for this layout.

Maybe something like the following:

openapi: 3.0.2
info:
  title: 'Distributed Knowledge Graphs'
  version: 1.0.0
x-walder-datasources:
  - http://127.0.0.1:8080/sample.ttl
  - https://natadimou.com/#me
paths:
  ...
#layouts can optionally be listed here to have queries defined
layouts:
  layout.pug:
    x-walder-query:
      ...