`CardanoDatabase` artifact identifiers have collisions

[jpraynaud]

Why

We have noticed that the CardanoDatabase artifact can have collisions on their identifiers. This happens when the same immutable file number is snapshot on two different epochs. This is also a source of flakiness in the CI.

What

Replace the identifier of the CardanoDatabase artifact to a hash computed from the merkle_root and the epoch

How

• Implement a new hash identifier for the CardanoDatabase artifact
• Update the HTTP routes
• Update the OpenAPI specs