Remove GeoCube

[danlooo]

A GeoCube is just raster data complying to:

• MUST be subtype of AbstractDimArray
• MUST have axis lon with tick values [-180,180] (WGS84)
• MUST have axis lat with tick values [-90,90] (WGS84)
• MAY have other axis (Time, altitude, ...)

There is no additional data being stored compared to a Raster or YAXArray{2}. Thus, let's remove that type and check on construction of the cell cube:

function CellCube(raster::AbstractDimArray; lon_name::Union{Nothing, String}=nothing, lat_name{Nothing, String}=nothing)
    if isnothing(lat_name)
    # search for common axis name e.g. YAXArrays.findAxis()
    end
  end
end

In addition, there is no need for DimensionalData.@dim, e.g. define specific dimensions for Q2DI axes. This info will be also lost during loading the dataset from disk.

[danlooo]

see #88