Split setup_and_run in multiple steps

This commit introduces more structure in ClimaEarth. It splits
`setup_and_run` in three functions:
- `setup`, which produces a `CoupledSimulation` (hence, it was renamed
to be `CoupledSimulation`, since it is just a constructor)
- `run!`, which runs the simulation. This is supported by the
introduction of `step!`, to take one single coupling step. This is
particularly useful in debugging
- `postprocess`, to make plots

The advantage of this separation is that one can now construct a
simulation without running it, and step a simulation one step at a time.
Both of these are particularly useful in interactive work and debugging.

This commit also renames `calendar_dt` to `diag_calendar_dt` to make it
clearer that it refers to diagnostics.

Author: Sbozzolo

NEWS.md

@@ -6,6 +6,21 @@ ClimaCoupler.jl Release Notes
 
 ### ClimaCoupler features
 
+### Split `setup_and_run` in multiple functions. PR[#1251](https://github.com/CliMA/ClimaCoupler.jl/pull/1251)
+
+`setup_and_run` was split into three functions:
+- `CoupledSimulation`, which takes a dictionary of a file path and constructs a coupled simulation
+- `run!`, which evolves the model
+- `postprocess`, which makes plots
+
+In addition to this, `step!` was introduced to take a single step forward with
+the coupled simulation.
+
+The function `setup_and_run` is still available.
+
+This change also renames `calendar_dt` to `diagnostics_dt` to make it clearer
+that it refers to diagnostics.
+
 ### Some misc. cleanup PR[#1244](https://github.com/CliMA/ClimaCoupler.jl/pull/1244)
 Changes include
 - Land simulation constructors no longer take in `domain_type`, which was unused.

experiments/ClimaEarth/run_amip.jl

@@ -43,4 +43,10 @@ include("setup_run.jl")
 config_file = parse_commandline(argparse_settings())["config_file"]
 
 # Set up and run the coupled simulation
-cs = setup_and_run(config_file)
+cs = CoupledSimulation(config_file)
+run!(cs)
+
+# Postprocessing
+# TODO: Remove this option?
+conservation_softfail = get_coupler_config_dict(config_file)["conservation_softfail"]
+postprocess(cs, conservation_softfail)