Previously "certutil" would generate a zip file if there were multiple
certificates.
However, this means that if the user specified "-multiple" or "-in"
then the output format will vary based on whether they entered
multiple instance names (-multiple) or whether the input file
contained multiple instance records (-in).
It is better if the output format is predictable based on the command
line options, so this change forces zip output whenever any of the
following command line options are supplied:
-pem
-keep-ca-key
-multiple
-in
Original commit: elastic/x-pack-elasticsearch@344baa5f17
eccf3899a2