Implement basic example with debugging module

[muuki88]

Most of the examples rely on a test placement with an active campaign.
This makes the examples fragile as there are a lot of factors that could cause no ad to be rendered.

In #5244 all example code was moved into this repository to make it easier to change.

🎯 Goal

Use the prebid debugging module as described in #5248 to decouple the dev-docs/examples/basic-example.md from appnexus.

Requirements

• we must make it very clear, what part of the example is non-production similar to the "not-for-prod.js" prebid distribution