Consensus data provider for Aura. This will always use slot 0 (used to determine the
index of the AURA authority from the authorities set by AURA runtimes) for the aura
digest since anvil-polkadot node will be the sole block author and AURA will pick
only its configured address, residing at index 0 in the AURA authorities set. When
forking from an assethub chain, we expect an assethub runtime based on AURA,
which will pick the author based on the slot given through the digest, which will
also result in picking the AURA authority from index 0.