refactor: KeyObject helper functions return JSCryptoKey

[DonIsaac]

What does this PR do?

Refactors helper functions in KeyObject.cpp to return JSCryptoKey objects instead of EncodeJSValues, along with some other minor refactors. Prereq refactor to KeyObject JS -> native migration. Part of #15585.

Note to reviewers: I recommend reviewing each commit individually.

How did you verify your code works?

Tests already exist for this logic.

[robobun]

❌ Your commit 907632e has 13 failures in #7629:

test/regression/issue/09041.test.ts - 1 failing on 🐧 3.20 x64-baseline

test/regression/issue/09041.test.ts - 1 failing on 🐧 3.20 x64

test/v8/v8.test.ts - 22 failing on 🐧 3.20 x64-baseline

test/v8/v8.test.ts - 22 failing on 🐧 3.20 x64

test/cli/hot/hot.test.ts - timeout on 🐧 24.04 x64

test/cli/hot/hot.test.ts - timeout on 🐧 3.20 aarch64

test/cli/hot/hot.test.ts - timeout on 🐧 3.20 x64

test/bundler/bundler_compile.test.ts - 1 failing on 🐧 20.04 x64-baseline

test/js/bun/spawn/spawn.test.ts - 1 failing on 🐧 24.04 aarch64

test/js/bun/util/sleep.test.ts - 1 failing on 🪟 2019 x64-baseline

test/integration/next-pages/test/next-build.test.ts - 1 failing on 🪟 2019 x64

test/integration/next-pages/test/next-build.test.ts - 1 failing on 🪟 2019 x64-baseline

test/js/web/fetch/fetch.test.ts - 1 failing on 🍎 14 aarch64

test/integration/next-pages/test/dev-server-ssr-100.test.ts - segmentation fault at address 0x20 on 🪟 2019 x64

test/cli/run/require-cache.test.ts - 1 failing on 🪟 2019 x64

test/cli/run/require-cache.test.ts - 1 failing on 🪟 2019 x64-baseline

test/js/node/test/parallel/test-crypto-keygen-async-named-elliptic-curve.js - SIGABRT on 🍎 13 aarch64

test/js/node/test/parallel/test-crypto-keygen-async-named-elliptic-curve.js - SIGABRT on 🍎 14 aarch64

test/js/node/crypto/crypto.key-objects.test.ts - SIGABRT on 🍎 13 aarch64

test/js/node/crypto/crypto.key-objects.test.ts - SIGABRT on 🍎 14 aarch64

test/js/node/crypto/crypto.key-objects.test.ts - code STATUS_STACK_BUFFER_OVERRUN on 🪟 2019 x64

test/js/node/crypto/crypto.key-objects.test.ts - SIGABRT on 🐧 22.04 aarch64

test/js/node/crypto/crypto.key-objects.test.ts - SIGABRT on 🐧 11 aarch64

test/js/node/crypto/crypto.key-objects.test.ts - SIGABRT on 🐧 12 aarch64

test/js/node/crypto/crypto.key-objects.test.ts - SIGABRT on 🐧 20.04 aarch64

test/js/node/crypto/crypto.key-objects.test.ts - SIGABRT on 🍎 13 x64

test/js/node/crypto/crypto.key-objects.test.ts - SIGABRT on 🐧 24.04 aarch64

test/js/node/crypto/crypto.key-objects.test.ts - SIGABRT on 🍎 14 x64

test/js/node/crypto/crypto.key-objects.test.ts - code STATUS_STACK_BUFFER_OVERRUN on 🪟 2019 x64-baseline

test/js/node/crypto/crypto.key-objects.test.ts - SIGABRT on 🐧 11 x64-baseline

test/js/node/crypto/crypto.key-objects.test.ts - SIGABRT on 🐧 12 x64-baseline

test/js/node/crypto/crypto.key-objects.test.ts - SIGABRT on 🐧 22.04 x64-baseline

test/js/node/crypto/crypto.key-objects.test.ts - SIGABRT on 🐧 11 x64

test/js/node/crypto/crypto.key-objects.test.ts - SIGABRT on 🐧 24.04 x64-baseline

test/js/node/crypto/crypto.key-objects.test.ts - SIGABRT on 🐧 12 x64

test/js/node/crypto/crypto.key-objects.test.ts - SIGABRT on 🐧 22.04 x64

test/js/node/crypto/crypto.key-objects.test.ts - SIGABRT on 🐧 20.04 x64-baseline

test/js/node/crypto/crypto.key-objects.test.ts - SIGABRT on 🐧 20.04 x64

test/js/node/crypto/crypto.key-objects.test.ts - SIGABRT on 🐧 24.04 x64

test/js/node/crypto/crypto.key-objects.test.ts - SIGABRT on 🐧 3.20 aarch64

test/js/node/crypto/crypto.key-objects.test.ts - SIGABRT on 🐧 3.20 x64

test/js/node/test/parallel/test-crypto-keygen-async-explicit-elliptic-curve.js - SIGABRT on 🍎 13 aarch64

test/js/node/test/parallel/test-crypto-keygen-async-explicit-elliptic-curve.js - SIGABRT on 🍎 14 aarch64

[cirospaciari]

Test failures

[cirospaciari]

I would choose another name here just to add what is being encoded and to what is being encoded example: encodeKeyObjectToJS