`ensemble_slice_model_simulation` is in order

Similarly to `ensemble_column_model_simulation`,

https://github.com/CliMA/OceanTurbulenceParameterEstimation.jl/blob/f7086e11e82e72f3bb7e533c6553ef9cac86031c/src/EnsembleSimulations.jl#L7

it'll be useful to add an `ensemble_slice_model_simulation`.

```julia
simulation = ensemble_slice_model_simulation(observations;
Nensemble = Nensemble,
architecture = architecture,
tracers = (:b, :e, :c),
free_closures = gent_mcwilliams_diffusivity,
additional_closures = closures::Tuple
)
```

There is an additional difficulty here: the slice simulations usually need to include more than one closures. That is, in the case of the mesoscale eddy fluxes closure we want to be able to calibrate for the `gent_mcwilliams_diffusivity` (`free_closures`) but allow for the model ensembles to also include other closures, same for all ensemble members (the `additional_closures`).

cc @glwagner

Start with src/EnsembleSimulations.jl at the referenced ensemble_column_model_simulation implementation. Trace how slice simulations represent free_closures and determine how additional_closures should be applied consistently across ensemble members. Done means ensemble_slice_model_simulation accepts the shown arguments and supports calibrating selected closures alongside shared additional closures.

Written by the indexing model from the issue text.