[red-knot] Simplify object out of intersections

[AlexWaygood]

Summary

object & int is equivalent to int, object & Unknown is equivalent to Unknown, object & ~int is equivalent to ~int... I could go on ;)

object is the top type, the supertype of everything, so it is always redundant in an intersection. Eagerly simplifying it out of intersections is easy, and fixes some property-test failures in another branch of mine.

Test Plan

• `cargo test -p red_knot_python_semantic --test mdtest
• QUICKCHECK_TESTS=200000 cargo test --release -p red_knot_python_semantic -- --ignored types::property_tests::stable
• uvx pre-commit run -a

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

[sharkdp]

I recently wrote this down (in an unpublished branch):

object describes the set of all possible values, while Never describes the empty set. The two types are complements of each other:

from knot_extensions import static_assert, is_equivalent_to, Not
from typing_extensions import Never

static_assert(is_equivalent_to(Not[object], Never))
static_assert(is_equivalent_to(Not[Never], object))

This duality is also reflected in other facts:

• Never is a subtype of every type, while object is a supertype of every type.
• Never is assignable to every type, while object is assignable from every type.
• Never is disjoint from every type, while object overlaps with every type.
• Building a union with Never is a no-op, intersecting with object is a no-op.
• Interecting with Never results in Never, building a union with object results in object.

Thanks for explicitly implementing the "intersecting with object is a no-op" part of this 👍

[sharkdp]

Thank you!