Update explorer for Cardano Blocks and Transactions

[jpraynaud]

Why

We need to update the explorer to support the new Cardano blocks and transactions certification.

What

Add a new Cardano Blocks and Transactions tab that list the signed sets of transactions (when activated on the aggregator) and a basic form to ask the aggregator for a proof of a subset of transactions or blocks.

How

• Activate the Cardano Blocks and Transactions tab when the aggregator is signing this type
• Add the list/detail of artifacts for Cardano Transactions
• Add a form to verify either a list of transactions or a list of blocks:
  • Selected with a dropdown menu if certification is done for blocks or transactions
  • Use the Mithril client WASM to do the retrieval of the proofs, of the certificate chain and their verification
  • Display a summary of the validated/invalidated transaction or block hashes (with their metadata: block number, slot number, ...)