Get an ICARUS certificate proxy

This is similar enough to SBND, that we refer to the documentation in there, with the following amendments:

• the virtual organization name is, unsurprisingly, icarus, which shows in the VOMS interface as /fermilab/icarus group.

• as a consequence, the correct ritual for summoning a certificate proxy ends with a different enchantment:

  kinit "${USER}@FNAL.GOV"                                                       # get your Kerberos authentication
  setup cigetcert                                                                # (if not already there)
  cigetcert -s 'fifebatch.fnal.gov'                                              # ask for a certificate
  voms-proxy-init -noregen -rfc -voms 'fermilab:/fermilab/icarus/Role=Analysis'  # create a "proxy" from the certificate
  

• the setup script is run with: source /cvmfs/icarus.opensciencegrid.org/products/icarus/setup_icarus.sh
• the information on production accounts does not apply to ICARUS at all and should not be relied upon: ask ICARUS production manager if you need information about that.