textual run --debug

[davetapley]

I use debugpy quite a lot.

A pattern I use is to give my apps a --debug switch and:

    if debug:
        click.secho('WAITING FOR DEBUGGER TO CONNECT', fg='yellow', bold=True)
        debugpy.listen(("localhost", 5678))
        debugpy.wait_for_client()

Then in VSCode I can launch this to attach:

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Python: Attach",
            "type": "python",
            "request": "attach",
            "justMyCode": false,
            "connect": {
                "host": "localhost",
                "port": 5678
            },
        }
    ]
}

I find it easier than launching directly from VSCode because I can just run the command I want from the terminal (with --debug) instead of having to go edit launch.json every time.

---

But sometimes I want to use textual run and textual console to build an MRE or test something out,
and (AFAIK) I can't get the benefit of console logging and breakpoints.

Accordingly, would you accept a PR to:

1. Check if debugpy is installed, and if it is:
2. Add a --debug option to textual run which would do that ⬆️ ?

Or, I welcome other ideas! 🙏🏻