Add support for pmtiles

[cboettig]

Thanks for this amazing package, really nice work and a very slick implementation! I really appreciate how you've managed to provide a quite native-R feeling interface while also letting us just drop back on list construction to access any edge case abilities in maplibre. Your documentation is impressive as well. 🌐

Here's a small tweak to resolve #8, adding support for PMTiles in the maplibre backend. By adding pmtiles.js, the existing utilities can work with pmtiles in much the same way as the vector tiles already included, e.g.:

maplibre(center=c(-72.9, 41.3), zoom=10) |>
  add_fill_layer(
    id = "redlines",
    source = list(type = "vector",
                           url = "pmtiles://https://data.source.coop/cboettig/us-boundaries/mappinginequality.pmtiles"),
    source_layer = "mappinginequality",
    fill_color = list("get", "fill")
  )

I know that #8 discusses the potential of pmtiles support for mapbox as well, but as this makes no changes to the R code base, I don't think this creates any divergence in the existing API. Thanks for considering this!

[walkerke]

Thank you, I'll take a look at this!

[walkerke]

This works great, thank you @cboettig!