feat(chain): introduce/build a bindex-rs PoC

**Describe the enhancement**

I recently came across https://github.com/romanz/bindex-rs during some discussion in Floresta Retreat.

As per the slides linked in it's README, there's some good improvements when benchmarked against other blockchain indexers implementations and I think it would be an interesting idea to play with it and come up with a PoC of integrating it to BDK, if it's even possible.

**Use case**

**Impact**
- [ ] Blocking production usage
- [x] Nice-to-have / UX improvement
- [ ] Developer experience / maintainability

**Are you using BDK in a production project?**
- [ ] Yes
- [ ] No
- [x] Not yet, but planning to (NOTE: the bindex-rs project does not have any BDK integration AFAIK)

**Which backend(s) are relevant (if any)?**
- [ ] Electrum
- [ ] Esplora
- [ ] Bitcoin Core RPC
- [ ] None / not backend-related (e.g. `bdk_chain`, `bdk_core`)
- [x] Other (please specify): A new backend implementation that integrates with bindex-rs

**Project or organization (optional)**

**Additional context**