Support range queries when fetching snapshots

[lemmih]

Issue summary

We currently ignore range queries when downloading snapshots from CloudFlare. Without range queries, we cannot resume downloads.

Tasks:

• Set up local development environment with wrangler dev.
• Download the latest calibnet snapshot from your local deployment. (This will use the forest-archive-dev bucket rather than the production forest-archive bucket).
• Confirm that range queries do not work.
• Extract range parameters from the HTTP request (see: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Range).
• Pass range parameters to R2.get (see: https://developers.cloudflare.com/r2/api/workers/workers-api-reference/#ranged-reads)
• Confirm that resume works.
• Confirm that downloading multiple chunks in parallel works (use aria2c -x5).

This is the R2.get method that needs range options:

forest-iac/cf/latest-snapshot/src/index.ts

Line 19 in 4a2d495

const object = await env.FOREST_ARCHIVE.get(latest.key);

Other information and links

R2 worker API: https://developers.cloudflare.com/r2/api/workers/workers-api-reference/

Logging headers to console: https://developers.cloudflare.com/workers/examples/logging-headers/

JavaScript library for parsing range headers: https://www.npmjs.com/package/range-parser