Put a certificate into the internal cache. This command might be useful if a client knows in advance certificates required for a test and wnats to make sure they get added to the internal cache. It is also helpful for debugging. To get the actual certificate, this command immediately inquires it using
S: INQUIRE TARGETCERT C: D <DER encoded certificate> C: END
Thus the caller is expected to return the certificate for the request as a binary blob.
The return code is 0 for success; i.e. the certificate has not been succesfully cached or one of the usual error codes from libgpg-error.