Modify test_dynamics.jl to includes tests for ShallowWaterModel

[francispoulin]

No description provided.

[glwagner]

Since our test scripts are already too long, I suggest creating a new script test_shallow_water_dynamics.jl. We also need this if we want to run the script in the shallow_water TEST_GROUP.

[navidcy]

Is this still outstanding?

[glwagner]

I'm closing this issue because I'm judging that it's not of current, timely relevance to Oceananigans development. If you would like to make it a higher priority or if you think the issue was closed in error please feel free to re-open.