[WIP] Step Over, Step Into, not working when debugging Subprocesses

[Copilot]

Thanks for assigning this issue to me. I'm starting to work on it and will keep this PR's description up to date as I form a plan and make progress.

Original issue description:

When debugging a process in python, the program halts on breakpoints yet only the Continue button works. Pressing Step Over or Step into just Continues to the next breakpoint.

I have tried many launch.json configs and the only thing that resolved my issue was downgrading to v2024.10.0.

here is my config just in case:

    {
        "name": "Python Debugger: Current File",
        "type": "debugpy",
        "request": "launch",
        "program": "app/main.py",
        "console": "integratedTerminal",
        "env": {
            "PYTHONPATH": "${workspaceFolder}"
        },
        "justMyCode": true,
        "subProcess": true,
        "steppingResumesAllThreads": false
    },

Fixes #1876.

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