Add plot dispatch on GeoAxis and Pyramid

If we would like to combine the pyramid data with data in other projections it would be best when the pyramid data is reprojected on the fly during interactions to the target projection of the plotting Axis. Therefore we would like to add this interaction into a dispatch of GeoAxis.
The code for the reprojection on the fly is

    on(ax.finallimits) do limits
        limext = Extents.extent(limits)
        # Compute limit in raster projection
        #todataproj = Proj.Transformation(plotcrs, rastercrs)
        #@show plotcrs, rastercrs
        trans = Proj.Transformation(plotcrs, rastercrs, always_xy=true)
        datalimit = trans_bounds(trans, limext)
        #datalimit = limext
        #@show datalimit
        if Extents.intersects(rasext, datalimit)
            rasdata = selectlevel(pyramids, datalimit)
            # Project selected data to plotcrs
            #data.val = rasdata
            data.val = Rasters.resample(rasdata, crs="EPSG:3857")
        end
        notify(data)
    end

This is from this commit: https://github.com/JuliaDataCubes/PyramidScheme.jl/blob/fb8eba07376f04aed3b424e2994321fee0b58f0f/src/PyramidScheme.jl

Parts of this are still in the source code and should be taken out.

Start with src/PyramidScheme.jl and the referenced commit, then trace the GeoAxis, Pyramid, and ax.finallimits interaction around selectlevel and Rasters.resample. Confirm how reprojection should be dispatched during limit changes and identify the leftover implementation that should be removed. Done means pyramid data is reprojected for the plotting axis during interactions without retaining obsolete source code.