Check identity of the Container parameter

[Zales0123]

Hello!

Thank you for the great library - it's a blessing while testing container configuration 🖖

I've encountered a problem when trying to test the compiler pass, that is setting an array parameter in the container. Its form was similar to ['key1' => 'value1', 'key2' => 'value2']. The order of key and elements was crucial. Using IsEqual constraint did not check it (the same case for a different type, e.g. '123' vs. 123).

Instead of the proposed solution, I also considered providing a new PhpUnit/*Constraint, but it seems like a little overcomplication.

Let me know if this change is something you would accept :) Thank you one more time 🚀