Allow user configuration of hybrid GSIBEC with GFS gaussian grid ensemble

[RussTreadon-NOAA]

GSIBEC PR #99 extends the GSIBEC ensemble interface to handle GFS gaussian grid files. This issue documents changes to parm templates to allow user configuration of hybrid GSIBEC DA using GFS gaussian grid ensembles.

[RussTreadon-NOAA]

Work for this issue will be done in feature/gau_gfsens

[RussTreadon-NOAA]

9a6989d alone does not activate the use of GFS gaussian ensembles via GSIBEC. The following change in parm/jcb-gdas/test/client_integration/gdas-atmosphere-templates.yaml activates GSIBEC GFS gaussian ensemble interface.

@@ -26,7 +26,7 @@ final_increment_file: atmosphere_final_increment_gaussian
 output_ensemble_increments_file: atmosphere_output_ensemble_increments_gaussian
 model_file: atmosphere_model_pseudo
 initial_condition_file: atmosphere_background
-background_error_file: atmosphere_background_error_hybrid_gsibec_bump
+background_error_file: atmosphere_background_error_hybrid_gsibec_gsibec

At present g-w change are needed to fully activate the GSIBEC GFS gaussian grid ensemble interface. See g-w issue #4863 for details.