Proposed work around for top level await in notebooks

[gziz]

As stated in #3885 and #3761, given the use of notebooks for the documentation, users may encounter errors if they try to use the code as-is in a Python file. This is because notebooks support top-level await statements, while Python files do not (without wrapping them in an async function).

When I need to use a .py file, I typically copy each code block from the notebook and wrap await statements inside an async function.

One proposal to improve this could be to include the full code from the notebook inside a dropdown at the bottom of the notebook.

```{dropdown} Full Code
:icon: code
```python
# Here goes the full code

Block of code with a handy copy button!