transform custom url schemes in style json before returning it

[achou11]

I wasn't aware that MapLibre dropped support for Mapbox's custom url scheme (e.g. mapbox://...). We should automatically transform any of these urls to normal http urls before returning the style json response.

Something similar to what https://github.com/rowanwins/maplibregl-mapbox-request-transformer does, basically.

[achou11]

More of a note to self but not having this may block us if we try to migrate comapeo-mobile to use MapLibre, as MapLibre React Native does not expose the transformRequest functionality that allows this to be done in userland (see maplibre/maplibre-react-native#424).

Can avoid being blocked by switching to a non mapbox style for the default online map, but that won't fix any issues related to custom styles that may reference mapbox styles using their custom protocol.

[achou11]

We should consider moving this to https://github.com/digidem/comapeo-map-server . Thoughts @gmaclennan ? EDIT: done

[achou11]

i did a brief exploration of using https://github.com/rowanwins/maplibregl-mapbox-request-transformer and came to the conclusion that we're probably better off writing/vendoring the transformation implementation ourselves, as it mostly assumes usage within a maplibre-gl app which unnecessarily pulls in a ton of deps.