Add a unit test for sha3

All tests are sourced from NIST via the Cryptographic Algorithm
Validation Program. They include namely:
1. the null data case
2. Input cases just above, equal, and below the rate block in bytes
3. Additional randomly sized vectors

ref: https://csrc.nist.gov/projects/cryptographic-algorithm-validation-program/secure-hashing

Author: rustaceanrob