Improve data access

[jsanz]

In order to scale better the website performance, we could consider switching from GeoJSON to flatgeobuff as it performs better and it is a more compact transport format.

Change should be pretty easy to do according to this snippet from the OpenLayers example:

// data source for map
const source = new ol.source.Vector({
    loader: async function () {
        // Fetch the flatgeobuffer
        const response = await fetch('/test/data/UScounties.fgb')
        // ...and parse all its features
        for await (let feature of flatgeobuf.deserialize(response.body)) {
            feature.getGeometry().transform('EPSG:4326', 'EPSG:3857')
            // add each feature to the map, after projecting it to
            this.addFeature(feature)
        }
    }
});

Opinions?

[jsanz]

Another option would be to research how to use PMTiles, probably through tippecanoe to produce a single file source of vector tiles that can be deployed easily as a static dataset.