Add analytic mountain wave tests

[dennisYatunin]

Purpose

Closes #3072.

To-do

• Move some of the plotting code to ClimaAnalysis.
• Check how the errors are affected by disabling DSS of metric terms and switching the velocity reconstruction.
• Add some documentation.

Content

• Adds a predicted_steady_state to the cache, which uses a custom linearization of our governing equations to approximate the steady-state velocity field.
• Adds plots for analyzing the discrepancies between the predicted velocity field and the actual velocity field.
• Adds a brief summary of the discrepancies that is printed at the end of the driver.

---

• I have read and checked the items on the review checklist.