Add diffusive wave testing for refactored networks

[BrianAvant]

Update the routing module/testing configuration to support diffusive wave testing on refactored networks.

[awlostowski-noaa]

Testing refactored hydrofabric with diffusive wave model

• After pulling refactored_routing branch and recompiling, I was able to run /Refactored_diffusive_Test.yaml with no problems
• I first ran a diffusive wave simulation for 288 timesteps (dt = 300 secs) with the refactored hydrofabric. The reach computations (serial) took 34.6 seconds. Results looked reasonable when plotted.
• I then ran a diffusive wave simulation for 288 timesteps (dt = 300 secs) with the native, non-refactored hydrofabric (/DOMAIN/Route_Link.nc). The reach computations (serial) took much longer - computation terminated after ~ 10 minutes.
• A MC simulation was run for the same time domain with the refactored hydrofabric took 0.2 seconds.