Reimplement data workflow with subdivision/indexing/cache

[twelch]

Need:

Previously there was a workflow that would subdivide vector data using PostGIS subdivision, use bundle-features to publish the data with an index (custom), and VectorDataSource to quickly fetch vector data using the index, given a bounding box and optionally merge the subdivided polygon back into a larger one. fetched results would be cached client-side to avoid extra re-fetches.

The previous solution:

• existed before Flatgeobuf and Cloud-optimized geotiff's with built-in index existed and were stable.
• only worked for polygon data, and not all polygons (were still some error cases)
• had a lot of manual scripted steps to manage it
• has suffered from bit rot, the bundle-features code no longer works, particularly the Slonik Postgres interface.

The problem:

• global datasets like political boundaries and shoreline have too large of polygons to be efficiently fetched for a lot of countries.

Immediate vector workaround solution:

• Subdivide dataset manually using whatever makes sense, doesn't have to be PostGIS, perhaps https://github.com/jvail/spl.js/
• publish subdivided flatgeobuf as normal (import:data/publish:data) and use getFeatures to fetch
• union result using Turf (likely much slower than VectorDataSource which can stitch back together subdivided quickly). Can we repurpose old union code?

Full replacement solution would:

• support both vector and raster
• JS client - build on top of or into Geoblaze and Flatgeobuf clients.
• client-side cache - will need to cache using a unique way to identify the range of data fetched (byte range? for flatgeobuf). And a way to read it back out client-side. Support reuse of cache across lambda invocations via shared global memory
• provide client-side caching
• Union - previous implementation could do this very quickly. Consider options - Turf could certainly do it.

References:

• https://github.com/flatgeobuf/flatgeobuf/blob/master/src/ts/http-reader.ts#L352