Fix HMAC empty hash function validation

[marko1olo]

Fixes #2513.

Summary

• validate the selected HMAC hashing function before calling toLowerCase()
• return a controlled OperationError for empty hash function values instead of an uncaught TypeError
• add a Node API regression test for chef.HMAC(..., { hashingFunction: "" })

Checks

• node --no-warnings --no-deprecation --openssl-legacy-provider tests/node/index.mjs -> 246 passing
• node --no-warnings --no-deprecation --openssl-legacy-provider tests/operations/index.mjs -> 1960 passing
• npx eslint src/core/operations/HMAC.mjs tests/node/tests/operations.mjs tests/operations/tests/Hash.mjs
• npx grunt configTests
• git diff --check

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