URL encoding for OCSP responder requests is broken

[azerbe]

Observed behavior

NATS does not properly encode the requests to an OCSP responder when doing revocation checks against a PKI. The base64 encoded certificate was missing. This can lead to problematic characters in the URL and failed revocation checks.

Expected behavior

NATS correctly encodes the request in the X.690 format as specified here: https://datatracker.ietf.org/doc/html/rfc6960#appendix-A.1

This is part of the ADR-38: OCSP Peer Verification feature.

Server and client version

NATS Version: 2.11.8

Host environment

NATS is running on Kubernetes in a single cluster with multiple servers. But it's irrelevant for this issue.

Steps to reproduce

1. Enable OCSP in the config and add the ocsp_peer config, like described in the ADR-38 document
2. Verify the requests on the PKI side. I know this is not easy to replicate, but I attached some screenshots of logs that show the incoming requests in detail.

The two requests at the bottom are from NATS and you can see the / in the request URL