PEM certificate
PKCS#8 public key PEM
This function will extract a public key from subjectPublicKeyInfo in the PEM certificate and convert it to PKCS#8 PEM public key.
0.2.0
certpem = "-----BEGIN CERTIFICATE-----MIIF4DCC..."
certtopkcs8pem(certpem) -> "-----BEGIN PUBLIC KEY-----..."
extract PKCS#8 public key PEM from certificate PEM