Variable explorer displays functions with a leading underscore

The `inspectVariables` request and the variable explorer panel in the debugger seems to display functions with a leading underscore.

Here's a simple repro

```
def _abc():
return "Hello"

def abc():
return "Hello"
```

In the above code snippet, `_abc` will appear in the "Variables" panel whereas `abc` will not, as demonstrated below


Start by tracing the `inspectVariables` request and the debugger's variable explorer panel, using the provided Python reproduction to compare how `_abc` and `abc` are displayed. Done means the variable panel handles both functions consistently with the reported expected behavior, with a regression test covering the reproduction.

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