Adding geodataframe to DataConversion

[hoxbro]

First part (1/2) of fix for https://discourse.holoviz.org/t/small-multiples-aka-facetted-plots/3760/2

This will make it possible to run:

import geopandas as gpd
import hvplot.pandas

countries = gpd.read_file(gpd.datasets.get_path('naturalearth_lowres'))
countries.hvplot(geo=True, by="continent")

I'm actually not sure if cuDF should be added to df_interfaces

Before fix:

After fix:

[codecov-commenter]

Codecov Report

Merging #5325 (6eaab76) into main (8d3a745) will decrease coverage by 0.04%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #5325      +/-   ##
==========================================
- Coverage   88.32%   88.29%   -0.04%     
==========================================
  Files         302      302              
  Lines       62579    62542      -37     
==========================================
- Hits        55272    55220      -52     
- Misses       7307     7322      +15     

Impacted Files	Coverage Δ
holoviews/core/data/__init__.py	86.53% <100.00%> (ø)
holoviews/core/data/pandas.py	93.47% <100.00%> (+0.29%)	:arrow_up:

... and 14 files with indirect coverage changes

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[maximlt]

I'm also unsure about supporting cuDF or other datatypes. We'll have to get this sorted out before the next release, I'd really like this fix to be part of it.

[maximlt]

@philippjfr we had a discussion about this a couple of weeks ago, can you remember what you decided about this? I remember there was a suggestion to move the interface from GeoViews to HoloViews. It would be nice if we could summarize the plan so that someone could pick up that work.

[jlstevens]

Other than a minor renaming suggestion, this new approach seems a lot more elegant! Looks good to me.