Mempool.space support

[darioAnongba]

Describe the enhancement
Hi all, my latest tests show that mempool.space does not work with bdk_esplora. The first error appearing is that mempool.space does not support the scripthash endpoints, only the address endpoints so we get this:

Cannot GET /api/v1/scripthash/.../txs as a 404
Also fee estimates does not work as the endpoint is not fee-estimates but fees/recommended.

I'll be very happy to work on this if it's decided to either add support to bdk_esplora or to create a dedicated bdk_mempool_space (valuable for websockets).

Use case
Esplora being too heavy on resources, it is not suitable for node runners. Most will directly connect to their node or use an indexer such as Electrum. Sadly Electrum or the node do not work on the browser for different reasons.
Mempool.space being a fork of Esplora, it exposes a REST API and a websocket API, ideal for browsers and Node through bdk-wasm.

Additional context
Mempool.space being a fork of Esplora, we could expect it to simply work out of the box yet it doesn't. People running their own node on Umbrel or Start9 can easily run their own mempool.space instance, as easily as running Electrs.

[ErikDeSmedt]

This work would also help bark.

We are heavily reliant on package-relay which is currently not supported by esplora. See PR.

Having the ability to use mempool.space would help us forward

[tnull]

I still think it wouldn't be great if we just gave up and accepted an even more fragmented protocol space as it will be even worse UX (note that many users already struggle understanding the difference between Electrum and Esplora). It may be worth reaching out to Blockstream folks to see if they'd be interested in migrating to the mempool fork, if Blockstream/electrs indeed is considered deprecated/unmaintained.