Testing FATES two-stream radiation scheme is activated by switching the fates_rad_model
parameter from 1 to 2.  This is all that is needed, both radiation schemes
1) Norman and 2) two-stream use the same optical parameters.

fates_rad_model

Note that to avoid exceeding the filename string length maximum, the parameter
file generated on the fly is placed in the $SRCROOT/src/fates/parameter_files
directory.  This may still run into problems is the $SRCROOT string is too long.

Like the test with seed dispersal activation, the main downside of this method is
that this file will require a custom update for every fates parameter file API update.
Allowing the HLM to generate the file at runtime via buildnamelist step
will provide the capability to build the fates parameter file on 
the fly which with the appropriate values for this test.

Note that the test as currently designed is not machine agnostic as it requires
specific shell commands for enabling the workflow to have access to ncgen.  Currently
this test is only usable on perlmutter.
