use .qmd as as full replacement of .ipynb

[tatakof]

hello!

wanted to know if it's possible to use only .qmd files for a full nbdev project (no .ipynb, all the code on .qmd) using nbdev's directives like so:

```{python}
#| default_exp core

\```

<some markdown>

```{python}
#| hide
from nbdev.showdoc import *

\```

<some markdown>

```{python}
#| export
def foo(): pass

\```

```{python}
#| hide
import nbdev; nbdev.nbdev_export()

\```
        

and get a result package with a core.py containing foo()

cheers,
Francis