fix(crypto): check x509 private keys

[andrewtdiz]

Summary

• adds bound X509Certificate#checkPrivateKey(privateKey) dispatch and property exposure
• validates pkey as a KeyObject and rejects public/secret KeyObjects with Node-shaped ERR_INVALID_ARG_VALUE
• compares RSA certificate public keys against the public key derived from a private KeyObject surrogate
• returns true for the matching RSA private key and false for mismatched RSA or unsupported non-RSA private keys
• adds focused Node/Perry parity coverage for success, mismatch, and validation behavior

Non-goals

• checkIssued()
• issuerCertificate
• infoAccess
• verify() covered by separate draft PR fix(crypto): verify x509 certificates with public keys #4300
• non-RSA private-key matching

Validation

• cargo fmt --all --check
• npm exec --package=node@26 -- node --experimental-strip-types test-parity/node-suite/crypto/x509/check-private-key.ts
• CARGO_TARGET_DIR=/root/perry-worktrees/.build-targets/perry-x509-check-private-key-check cargo check -p perry-stdlib --no-default-features --features crypto
• CARGO_TARGET_DIR=/root/perry-worktrees/.build-targets/perry-x509-check-private-key-build cargo build -p perry --release
• CARGO_TARGET_DIR=/root/perry-worktrees/.build-targets/perry-x509-check-private-key-build cargo build -p perry-runtime -p perry-stdlib --release
• direct Perry run of test-parity/node-suite/crypto/x509/check-private-key.ts
• PATH=<node26-bin>:$PATH CARGO_TARGET_DIR=/root/perry-worktrees/.build-targets/perry-x509-check-private-key-build PERRY_RUNTIME_DIR=/root/perry-worktrees/.build-targets/perry-x509-check-private-key-build/release PERRY_NO_AUTO_OPTIMIZE=1 PERRY_GEN_GC=0 ./run_parity_tests.sh --suite node-suite --module crypto --filter x509/check-private-key
• git diff --check
• ./scripts/check_file_size.sh