Modify all tests to panic instead of returning an error

[hug-dev]

Test functions (with #[test]) should ideally panic when there is an error instead of return a Result and using ?. That way it is easy to see which line exactly failed.

[ionut-arm]

We could actually take inspiration from the work @wiktor-k did for the cryptoki crate: parallaxsecond/rust-cryptoki#39

Instead of using unwrap, we can create our own error type and implement a conversion from any usual types implementing the Error trait to panic and log the error. This way we get the best of both worlds - easy handling with ? and error messages that point to relevant lines in tests.