New example pages: HTTP errors

[julien-deramond]

Prerequisites

• I have searched for duplicate or closed feature requests
• I have read the contributing guidelines

Proposal

This feature request is rather simple to explain since the idea would be to provide in our examples how to render HTTP errors such as a 404 not found page, 500 internal error, etc.

Motivation and context

This is a highly-reusable template that can bring some consistency across Orange digital products.