Encapsulate AxisTensor components

[charleskawczynski]

A common pattern for users is to dive all the way into the backing SArray's data of an AxisTensor. For example, in ClimaAtmos: ᶠϵ₂₃ = ᶠϵ.components.data.:6.

We should probably internalize these data accesses with some API.

One reason that this is problematic is that it could also depend on the DataLayout. For example:

ᶜΔz = Fields.local_geometry_field(Y.c).∂x∂ξ.components.data.:9

is only correct for certain geometric points. ClimaCore has a general version of this:

Δz_metric_component(::Type{<:Geometry.LatLongZPoint}) = 9
Δz_metric_component(::Type{<:Geometry.Cartesian3Point}) = 1
Δz_metric_component(::Type{<:Geometry.Cartesian13Point}) = 4
Δz_metric_component(::Type{<:Geometry.Cartesian123Point}) = 9
Δz_metric_component(::Type{<:Geometry.XYZPoint}) = 9
Δz_metric_component(::Type{<:Geometry.ZPoint}) = 1
Δz_metric_component(::Type{<:Geometry.XZPoint}) = 4

"""
    Δz_data(space::AbstractSpace)

A DataLayout containing the `Δz` on a given space `space`.
"""
function Δz_data(space::AbstractSpace)
    lg = local_geometry_data(space)
    data_layout_type = eltype(lg.coordinates)
    return getproperty(
        lg.∂x∂ξ.components.data,
        Δz_metric_component(data_layout_type),
    )
end

[charleskawczynski]

Another pattern that we should probably fix/internalize is:

        ∂x∂ξ_level = local_geometry_level.∂x∂ξ.components.data
        end_index = fieldcount(eltype(∂x∂ξ_level)) # This will be 4 in 2D and 9 in 3D.
        ∂x³∂ξ³_level = ∂x∂ξ_level.:($end_index)