[WIP] Update Open Street Map examples to use spatialpandas

[jonmmease]

WIP PR to update the Open Street Map examples (1 billion and 3 billion) to use spatialpandas rather than the legacy datashader.spatial module:

TODO:

• [ ] Upload the two new parquet datasets to the datashader-data s3 bucket. @jlstevens can you give me access? Note, I'm planning to give the new files a different name so that the old examples tutorial will still work. (New names osm-1b.parq and osm-3b.parq.)
• [ ] DaskGeoDataFrame support in HoloViews is still needed to make the interactive HoloViews examples work. See https://github.com/holoviz/holoviews/issues/4234.
• [ ] Update census example as well: https://examples.pyviz.org/census/census.html.

[jbednar]

Thanks; I've requested S3 access for you. For the new names, I suggest osm-1b.parq and osm-3b.parq. What about the Census dataset?

[jonmmease]

For the new names, I suggest osm-1b.parq and osm-3b.parq.

Sounds good

What about the Census dataset?

Ah, right. I forgot that one had a datashader.spatial dataset. I added another TODO above.

[maximlt]

It looks like part of the changes made in this PR were also made in this mega PR, hence the conflicts. It seems though that some more changes were planned in this PR, they'll need a closer look.

Pinging @ianthomas23 as this example (OSM 1B and OSM 3B) use datashader and spatialpandas, looking at them you may have ideas for potential improvements.

[jonmmease]

Closing to clean up my PR history, but feel free to re-open if someone wants to pick this up again.