Activate WebCryptoAPI/import_export/importKey_failures.js test

[olegbespalov]

What?

While we implemented support for elliptic curve algorithms (#67 and #69), we missed the Web Platform Test WebCryptoAPI/import_export/importKey_failures.js, which tests some negatives for the import keys.

It is worth activating it (please see https://github.com/grafana/xk6-webcrypto/tree/main/webcrypto/tests), which probably could also cause some adjustments in implementation.

At the moment of writing issue, we do support two algorithms from there (ECDH and ECDSA), but depending on the state of the extension, it could be more.

Why?

Testing against the Web Platform Test suite is essential since it gives some confidence about the implementation.