feat(expect): warn on toEqual comparing non-plain objects with empty Object.keys

[ViniciusDev26]

Description

Adds isPlainObject and isNonPlainEmptyObject helpers to jest-utils and emits a console.warn in toEqual when the actual value
is a non-plain object with no enumerable keys, preventing silent false-negatives (e.g. Response).

Example of the false-negative this addresses:

// This test passes silently today, but should not:
const r1 = new Response("hoge", { status: 200 })
const r2 = new Response(null, { status: 404 })
expect(r1).toEqual(r2) // ⚠ no properties compared                                                                                      

Resolves #9542

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[sheremet-va]

The issue has a comment on the board:

have a builtin response/request check, check what node does in assert

We want to process Response/Request/Headers inside the equals function. And we need to validate how the native assert in Node works with those already

We don't want to add the empty check guard