crypto: add experimental warning to crypto.webcrypto

[panva]

This adds a once-per-process ExperimentalWarning when Web Crypto API is accessed.

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• commit message follows commit guidelines

[nodejs-github-bot]

Review requested:

• @nodejs/crypto

[panva]

meh, i'm getting the experimental warning even by just requiring crypto, not when accessing webcrypto...

--trace-warnings

(node:22870) ExperimentalWarning: Web Crypto API is an experimental feature. This feature could change at any time
    at emitExperimentalWarning (node:internal/util:183:11)
    at node:internal/crypto/webcrypto:6:1
    at NativeModule.compileForInternalLoader (node:internal/bootstrap/loaders:278:7)
    at nativeModuleRequire (node:internal/bootstrap/loaders:307:14)
    at lazyRequire (node:internal/crypto/util:63:36)
    at Object.get [as webcrypto] (node:crypto:285:20)
    at get (<anonymous>)
    at getOwn (node:internal/bootstrap/loaders:152:5)
    at NativeModule.syncExports (node:internal/bootstrap/loaders:260:31)
    at ModuleWrap.<anonymous> (node:internal/bootstrap/loaders:240:22)

seems to be a sideproduct of ESM's syncExports? Not sure how to proceed from here.

[panva]

@guybedford I don't want to pollute the other PR we engaged in. So here I'd like to make the crypto.webcrypto getter emit an ExperimentalWarning. Making the property non-enumerable means it won't be importable in ESM modules and pushing the warning to a subproperty of webcrypto doesn't feel right. As-is the warning is emitted even when just requiring 'crypto'.

Any other ideas?

[panva]

Closing for clear lack of interest.