Feature request: support DER certificates for kw.crypto.verifyCert() function

[viccuad]

Currently, only PEM certificates are accepted in kw.crypto.verifyCert() CEL function.

Acceptance criteria

• Expand the library to also accept DER certificates. This can be done by overloading the kw.crypto.verifyCert() function.
• The go sdk expects `crypto.Certificate{} struct for both the certificate to be verified and the certificate chain to verify against. This Certificate has an enum field (PEM, DER) and accepts []bytes. Register the corresponding int constants for the enum, and do the casting to []bytes correctly.
• Ensure that both types of encoding for the certificates can be used interchangeably.
• Provide unit tests.
• Provide e2e tests.