Add testing of built reports

[enryH]

Once we get into a bit more stable version, we could test that

• qmd- files for certain reports are unchanged
• streamlit folder contents are the same

the header for qmd notebooks changes according the selected quarto report type. For revealjs the body changes as well.

empy folders with only a description

related to #108

• no overview section should be generated

The basic example to include some components on the section folders and maybe even root of the example. But for the root, we maybe should have an even simpler example

root
|-- folder
|-  | - description.md
|--description.md

[enryH]

This was now started as part of styling and organizing the repository in #131.