crypto: graduate WebCryptoAPI Ed25519 and X25519 algorithms as stable

[panva]

Ed25519 and X25519 algorithms are no longer experimental. They were merged into the main spec.

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https://github.com/nodejs/node/labels/notable-change

Following the merge of Curve25519 into the Web Cryptography API Editor's Draft the Ed25519 and X25519 algorithm identifiers are now stable and will no longer emit an ExperimentalWarning upon use.