rft: split Smagorinsky diffusive model to horizontal and vertical components

[haakon-e]

This pull request extends the configurability of the Smagorinsky-Lilly turbulence model by allowing users to specify whether the model should be applied in the horizontal direction only, vertical direction only, both together, or each separately. This enhancement is reflected in configuration options, documentation, and the underlying implementation.

Smagorinsky-Lilly model configurability:

• Added support for new configuration options for the Smagorinsky-Lilly model: UV (horizontal only), W (vertical only), and UV_W (horizontal and vertical treated separately), in addition to the existing UVW (all directions). (config/default_configs/default_config.yml, src/solver/model_getters.jl, src/solver/types.jl) [1] [2] [3]
• Updated the assertion in get_smagorinsky_lilly_model to allow the new configuration symbols. (src/solver/model_getters.jl)
• Improved documentation for the Smagorinsky-Lilly model to describe all possible configuration flags and their effects. (src/solver/model_getters.jl, src/solver/types.jl) [1] [2]

Implementation logic:

• Updated logic in set_smagorinsky_lilly_precomputed_quantities! to correctly compute horizontal and vertical length scales (ᶜL_h, ᶜL_v) depending on the chosen model configuration. (src/parameterized_tendencies/les_sgs_models/smagorinsky_lilly.jl)
• Modified the is_smagorinsky_vertical and is_smagorinsky_horizontal helper functions to recognize the new configuration options. (src/solver/types.jl) [1] [2]

[haakon-e]

This change is part of the following stack:

• rft: separate vertical and full strain #4073
  • rft: smagorinsky-lilly for future h-v splitting #4074
    • rft: split Smagorinsky diffusive model to horizontal and vertical components #4054 ◀

_{Change managed by git-spice.}

[trontrytel]

Thank you!