crypto: refactor keyObject.toCryptoKey() and SubtleCrypto.getPublicKey()

[panva]

Move KeyObject.prototype.toCryptoKey() onto the base KeyObject class and dispatch from the cached native key type. Both secret and asymmetric conversions now pass a KeyObjectHandle through the Web Crypto import paths.

Expose KeyObjectHandle.prototype.getKeyType() so asymmetric importers can validate public/private usages without wrapping the handle back into a KeyObject. Secret importers likewise consume KeyObjectHandle directly.

Use the shared asymmetric conversion helper to derive public CryptoKeys for SubtleCrypto.getPublicKey(), avoiding the temporary PrivateKeyObject/createPublicKey round trip while keeping usage validation in the import path.

Update getPublicKey and KeyObject.toCryptoKey tests to be driven from the Web Crypto supported-algorithm registry so new algorithms require either coverage or an explicit skip.

Resolves this TODO:

node/lib/internal/crypto/webcrypto.js

Lines 1472 to 1475 in d854212

	// TODO(panva): this is by no means a hot path, but let's still follow up to get
	// rid of this awkwardness
	const keyObject = createPublicKey(new PrivateKeyObject(getCryptoKeyHandle(key)));
	return keyObject.toCryptoKey(getCryptoKeyAlgorithm(key), true, usages);

[nodejs-github-bot]

Review requested:

• @nodejs/crypto

[codecov]

Codecov Report

❌ Patch coverage is 97.80702% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.30%. Comparing base (8d0a3b8) to head (ca3bfce).
⚠️ Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/internal/crypto/keys.js	97.91%	4 Missing ⚠️
src/crypto/crypto_keys.cc	85.71%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #63622   +/-   ##
=======================================
  Coverage   90.29%   90.30%           
=======================================
  Files         730      730           
  Lines      234782   234814   +32     
  Branches    43953    43961    +8     
=======================================
+ Hits       211993   212044   +51     
+ Misses      14501    14479   -22     
- Partials     8288     8291    +3     

Files with missing lines	Coverage Δ
lib/internal/crypto/aes.js	92.19% <100.00%> (-0.06%)	⬇️
lib/internal/crypto/cfrg.js	94.63% <100.00%> (-0.05%)	⬇️
lib/internal/crypto/chacha20_poly1305.js	98.46% <100.00%> (-0.02%)	⬇️
lib/internal/crypto/ec.js	95.50% <100.00%> (-0.05%)	⬇️
lib/internal/crypto/mac.js	99.01% <100.00%> (-0.01%)	⬇️
lib/internal/crypto/ml_dsa.js	97.44% <100.00%> (-0.03%)	⬇️
lib/internal/crypto/ml_kem.js	95.45% <100.00%> (-0.04%)	⬇️
lib/internal/crypto/rsa.js	94.44% <100.00%> (-0.04%)	⬇️
lib/internal/crypto/webcrypto.js	97.11% <100.00%> (-0.01%)	⬇️
src/crypto/crypto_keys.h	65.11% <ø> (ø)
... and 2 more

... and 36 files with indirect coverage changes

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