Loads the certificate signing request referenced by the csr_serial context
parameter from the database and hands it to the configured NICE backend.
Note that it highly depends on the implementation what properties are taken from
the pkcs10 container and what can be overridden by other means.
The activity allows request types spkac and pkcs10 - you need to adjust this
if you use other formats.
See documentation of the used backend for details.
See OpenXPKI::Server::Workflow::NICE::issueCertificate for details