fix(toCotainKeys): should not throw when actual is undefied

[yosrayousfi]

What

Bug.

Why

expect.toContainKeys throws when actual is undefined.

Reproduction steps

expect({}).toEqual({
    expectedObject: expect.toContainKeys(["expectedProperty"]),
});

Actual behavior

An error is thrown.

Expected behavior

Displaying actual/expected diff.

Notes

Housekeeping

• Unit tests
• Documentation is up to date
• No additional lint warnings
• Typescript definitions are added/updated where relevant

[SimenB]

thanks!