[red-knot] Infer unary not operation for instances

[Glyphack]

My attempt at resolving not op for instances.

The type is true unless one of the following happens:

1. We call the __bool__ and if it is false then the result is false.

Test Plan

I added a new test case with some examples from these resources:

• https://docs.python.org/3/library/stdtypes.html#truth-value-testing
• https://docs.python.org/3/reference/datamodel.html#object.__len__
• https://docs.python.org/3/reference/datamodel.html#object.__bool__

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

[carljm]

Thanks for working on this! Left a few comments. The good news is I think the comments should make the implementation much simpler.

[carljm]

Looks great, thank you!!

Only minor wording nits and one other comment; I'll just apply these and look into the call_dunder question briefly, and then land this.

[Glyphack]

Thanks for helping me why my initial approach was wrong. I will try to make it less work for you next time.

[carljm]

Thanks for helping me why my initial approach was wrong. I will try to make it less work for you next time.

No problem, thank you for the contributions!!

[carljm]

Also, to be clear, your initial approach was wrong mostly because we had a TODO comment in the source code specifically suggesting the wrong approach 😆