Indirection layer for node

[avnik]

This PR include:

• bump of kupo (existing url pointed to non-exist file, so I fixed and updated it)
• add indirection layer for cardano.providers.node (and switch oura into it to test)
• add demeter-run module (as alternative "provider" for node)

TODO:

• switch kupo, blockfrost and ogmios to use "providers"
• Implement providers for kupo, blockfrost and ogmios

[TotallyNotChase]

I like the indirection here. I assume it allows some abstraction to easily switch out providers. This is how Atlas and similar Haskell frameworks work as well so it's very nice.

[aciceri]

This PR does several different unrelated things:

• bump kupo: approved 👍
• add demeter package: approved 👍
• add demeter service: seems good, if it works it's approved 👍
• indirection layers: am I understanding it wrong or it would be useful only for demeter? You can use it choosing between different providers (including cardano-node), right? Could you please provide an example where this new layer is useful?
  Also, since you changed the oura module, it's already implicitly tested by the oura test but would it be possible to have a more specific test?
• fix the docs generation: what caused this? Did you update the nixpkgs input? Honestly I can't understand why it was failing and why now it works but I'm happy if now works.

I don't want to slow down this so I can already merge if you think it's ready, I only ask to create issues for what we are missing if we choose to merge (different issues since they can be worked on in parallel, so PRs last less hopefully) i.e.

• implement a test for demeter
• implement options.cardano.demeter-run.kupo (with a test)
• implement options.cardano.demeter-run.ogmios (with a test)
• make kupo, blockfrost and ogmios use the new indirection layer