Adding integration test suite

[stevedoyle]

This is a WIP PR to get feedback on an approach to add a test suite for wasi-crypto (issue#44).

It is based on using the wycheproof test vecors to test wasi-crypto implementations for the algorithm set that is covered by the wycheproof test vectors. To get some initial feedback, Rust "integration tests" have been added for AES-128-GCM, AES-256, CHACHA20-POLY1305, HMAC/SHA-256, HMAC/SHA-512 and HKDF with SHA-256 and SHA-2512.

To run the tests:
cargo wasi test --test test_symmetric

These have been tested with WasmEdge.

[jedisct1]

Hi Steve!

And sorry for the delay, I'm still in Tokyo for HACS.

Running the Wycheproof test vectors is good.

However this is testing the underlying crypto libraries (which should hopefully already include these vectors in their own test suite), not the wasi-crypto API.

We need tests specific to the API to check for interoperability between runtimes, even if they use the same crypto library under the hood.

For example:

• Passing invalid handles
• Not setting a nonce for an AEAD that requires one
• Invalid keys, invalid encodings
• Closing handles twice
• Invalid operation sequences
• Invalid algorithm names, or names from one category of algorithmes used with a function for a different category
• ...