Set the initial conditions inside of StaircaseDNS

[jbisits]

For the method where model_setup is passed it makes sense to do this because the initial conditions are needed to setup either the boundary conditions or the background state.

[jbisits]

These two

StaircaseShenanigans.jl/src/staircase_model.jl

Lines 21 to 44 in 51aa789

	"Build the model from `model_setup` then return a `StaircaseDNS`, mainly used to build
	the `model` with [reentrant_boundary_conditions](@ref) `boundary_conditions` from `initial_conditions`."
	function StaircaseDNS(model_setup::NamedTuple, initial_conditions, initial_noise)
	boundary_conditions = reentrant_boundary_conditions(initial_conditions)
	architecture, diffusivities, domain_extent, resolution, eos = model_setup
	model = DNSModel(architecture, domain_extent, resolution, diffusivities, eos; boundary_conditions)
	return StaircaseDNS(model, initial_conditions, initial_noise)
	end
	"`StaircaseDNS` that is `Periodic` in z direction and evoloves an anomaly around a
	background state."
	function StaircaseDNS(model_setup::NamedTuple, initial_conditions::PeriodoicSingleInterfaceICs, initial_noise)
	architecture, diffusivities, domain_extent, resolution, eos = model_setup
	z_topology = Periodic
	τ = diffusivities.κ.S / diffusivities.κ.T
	background_fields = S_and_T_background_fields(initial_conditions, domain_extent.Lz, τ)
	model = DNSModel(architecture, domain_extent, resolution, diffusivities, eos;
	z_topology, background_fields)
	return StaircaseDNS(model, initial_conditions, initial_noise)
	end