Support for Cloudflare's D1 and/or R2

## Feature Description

Cloudflare has been developing an alternative to traditional storage providers, with the benefit that it has no egress fees for the data.

- [**D1**](https://developers.cloudflare.com/d1) is a relational database build on SQLite, which currently is on Alpha. It can be access and manipulated through the online GUI on [Cloudflare's Dashboard](https://dash.cloudflare.com/) or through the CLI using a npm package called [wrangler](https://github.com/cloudflare/workers-sdk/tree/main/packages/wrangler).
- [**R2**](https://developers.cloudflare.com/r2) is the Cloudflare's implementation of an object storage service. It can be used through the GUI on [Cloudflare's Dashboard](https://dash.cloudflare.com/), through the CLI with [wrangler](https://github.com/cloudflare/workers-sdk/tree/main/packages/wrangler), or using the [Amazon's S3 API](https://aws.amazon.com/s3/).

## Proposal

1. First the easiest, R2. To begin with, test if Apache Libcloud [`libcloud.storage.drivers.s3`](https://libcloud.readthedocs.io/en/stable/apidocs/libcloud.storage.drivers.html#module-libcloud.storage.drivers.s3) works correctly with an R2 bucket, and if so, update the documentation to reflect that said module can be used with R2. It would be a good idea to document what functions are NOT available, according to Cloudflare's R2 [documentation](https://developers.cloudflare.com/r2/data-access/s3-api/api/).
2. If `libcloud.storage.drivers.s3` doesn't work with R2, another module can be created (`libcloud.storage.drivers.r2`, for example), which is based on the S3's module but with a few adjustments, and removing functions that are unavailable on R2. I do think this is a cleaner solution, to keep S3 separated from R2.
3. Finally, as Apache Libcloud does not (yet) manage Cloud Databases, a fine addition to the library would be to start a new module (maybe `libcloud.sql.*`?) and implement certain popular SQL Databases, such as [Amazon's RDS](https://aws.amazon.com/rds/), [Azure's SQL Database](https://azure.microsoft.com/en-us/products/azure-sql/database/), and of course Cloudflare's D1.

Beginnen Sie mit der Prüfung von libcloud.storage.drivers.s3 anhand der Dokumentation zur S3 API von Cloudflare R2 und stellen Sie fest, ob die bestehende Kompatibilität dokumentiert werden kann oder ein separates Modul libcloud.storage.drivers.r2 benötigt wird. Der weiter gefasste Vorschlag sieht außerdem vor, libcloud.sql.* für D1 und andere verwaltete SQL-Datenbanken zu entwerfen; als abgeschlossen gilt dies, wenn Umfang, Implementierung, Tests und Dokumentation abgestimmt sind.

Vom Indexierungsmodell aus dem Issue-Text verfasst.