Generate annotated notebook with embedded flake8 reports about flake8-nb HOT 2 OPEN

I'm not too sure about this feature 🤔
While I see the usefulness, I also see the problems in having a CLI linting tool manipulate a notebook (at least for now).

1. Running a CLI tool on a notebook that changes it on disk, can leave you in limbo (true for all CLI tools). For example, imagine the following scenario:

• You have unsaved changes, so the CLI tool does only knows about the saved changes.
• Based on that knowledge it changes the notebook, which might lead to data loss.
• You get prompted the "File changed do you want to 'Reload', 'Overwrite' or 'cancel' "
  The only clean way to prevent a scenario like this would be via an editor plugin that uses the following steps:
• Save the notebook
• Run the CLI tool
• Reload the notebook from disk
  If you know a plugin that allows running an arbitrary CLI tool in that way please tell me 😄

2. There already is jupyterlab-flake8 which directly gives you feedback in your notebook.

So at least until there is an editor plugin that could prevent such a scenario (e.g. for jupyterlab) I would put this on halt (if you really want this, PR's are welcome 😉 ).

from flake8-nb.

Re: overwriting - I generally get my cli tools to have an option to write to a new file, or even to a new default output file (out.py, ORIGINAL_FILENAME-revised.py etc).

If I get anywhere with a PR, I'll let you know...

from flake8-nb.