Update combine_surfaces!

[LenkaNovak]

Before running the functionality that calculates fluxes over multiple arbitrary surfaces, as specified in #311 , we need to update combine_surfaces! and update_surface_fractions. This includes a new Interfacer module that prescribes the component model interfaces. This is a prequel to the ClimaEarth.jl design, and a step towards having a source code that has no dependencies on the data structures of the underlying component models.

Components

• update code with interface changes
• add unit tests for Interfacer
• update slabpanet
• update AMIP

QA

• the same behavior compared to current main recovered
  • conservation
  • AMIP paperplots
• comparable performance to the current main
• CI unit tests pass

Note on the design

• we're using a function get_field(sim::ComponentModelSimulation, ::Val(:{field_of_interest})) for now, which allows model-agnostic field specification, as well as definition of wrapper methods, such as get_field(sim::ComponentModelSimulation, ::Val, colidx). While we could define variable-specific functions, e.g. get_termperature, and use anonymous functions for the wrapper functions, the wrapper functions would be less transparent and may cause conflicts with methods of the same signature. Alternatively, we could define each variable as a struct object upon which we dispatch, but this adds a bit more code and less flexibility when developing. The current solution seems like a good temporary compromise.