* Add sha256 SASL helper
* Rename internal createHMAC(...) to hmacSha256(...)
* Add parseAttributePairs(...) helper for SASL
* Tighten arg checks in SASL xorBuffers(...)
* Add SASL nonce check for printable chars
* Add SASL server salt and server signature base64 validation
* Add check for non-empty SASL server nonce
* Rename SASL helper to parseServerFirstMessage(...)
* Add parameter validation to SASL continueSession(...)
* Split out SASL final message parsing into parseServerFinalMessage(...)
* Fix SCRAM tests
Removes custom assert.throws(...) so that the real one from the assert package is used and
fixes the SCRAM tests to reflect the updated error messages and actual checking of errors.
Previously the custom assert.throws(...) was ignoring the error signature validation.
