Extract-certs-pem writes pem files to a dedicated file; since it does
not really work in cluster-environments it was never super helpful.
This commit deprecates this file and, instead, adds
log-certs-base64.zeek, which adds the base64-encoded certificate (which
is basically equivalent with a PEM) to the log-file. Since, nowadays,
the log-files are deduplicates this should not add a huge overhead.
