Add .env support to the example implementations

[andig]

This simplifies testing. Happy to provide a PR.

[DerAndereAndi]

Thanks for your suggestion. The examples are not meant to be used for active testing as they only show how to basically use the API and have a quick demo running. They are not meant to be fully functional and implement the use cases fully or even partly.

If you need something for testing, I would recommend to use the examples as a foundation to build your own test setup with the functionality you need.