crypto: fix webcrypto derive key lengths

[panva]

This implements the get key length operation of possible deriveKey derived key's algorithms.

Specifically, for

AES Keys

PBKDF2 and HKDF Keys

Return null.

HMAC Keys

[nodejs-github-bot]

Review requested:

• @nodejs/crypto

[panva]

Prior to this code in place the following, which works in the browser

const alice = await crypto.subtle.generateKey({ name: 'ECDH', namedCurve: 'P-256' }, false, ['deriveKey']);

const bob = await crypto.subtle.generateKey({ name: 'ECDH', namedCurve: 'P-256' }, false, ['deriveKey']);

const alice_ecdh_params = { name: 'ECDH', public: bob.publicKey };
const alice_shared_key = await crypto.subtle.deriveKey(alice_ecdh_params, alice.privateKey, 'HKDF', false, ['deriveKey']);

Failed in Node.js with

TypeError [ERR_INVALID_ARG_TYPE]: The "length" argument must be of type number. Received undefined
    at __node_internal_captureLargerStackTrace (node:internal/errors:465:5)
    at new NodeError (node:internal/errors:372:5)
    at __node_internal_ (node:internal/validators:103:13)
    at Object.asyncDeriveBitsECDH (node:internal/crypto/diffiehellman:435:5)
    at SubtleCrypto.deriveKey (node:internal/crypto/webcrypto:184:10)
    at REPL10:1:83 {
  code: 'ERR_INVALID_ARG_TYPE'

Because the length passed to asyncDeriveBitsECDH was undefined rather than the expected null which indicates to give us everything that is generated.

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/43247/

[nodejs-github-bot]

Landed in 18bd02f