feat(cumulus): Adds support for additional relay state keys in parachain validation data inherent (#9262)

Adds the possibility for parachain clients to collect additional relay
state keys into the validation data inherent.

With this change, other consensus engines can collect additional relay
keys into the parachain inherent data:
```rs
let paras_inherent_data = ParachainInherentDataProvider::create_at(
  relay_parent,
  relay_client,
  validation_data,
  para_id,
  vec![
     relay_well_known_keys::EPOCH_INDEX.to_vec() // <----- Example
  ],
)
.await;
```

Author: RomarQ

cumulus/client/consensus/aura/src/collator.rs

@@ -137,6 +137,7 @@ where
 			relay_parent_descendants
 				.map(RelayParentData::into_inherent_descendant_list)
 				.unwrap_or_default(),
+			Vec::new(),
 		)
 		.await;
 

cumulus/client/parachain-inherent/src/lib.rs

@@ -39,6 +39,7 @@ async fn collect_relay_storage_proof(
 	relay_parent: PHash,
 	include_authorities: bool,
 	include_next_authorities: bool,
+	additional_relay_state_keys: Vec<Vec<u8>>,
 ) -> Option<sp_state_machine::StorageProof> {
 	use relay_chain::well_known_keys as relay_well_known_keys;
 
@@ -133,6 +134,13 @@ async fn collect_relay_storage_proof(
 		relevant_keys.push(relay_well_known_keys::NEXT_AUTHORITIES.to_vec());
 	}
 
+	// Add additional relay state keys
+	let unique_keys: Vec<Vec<u8>> = additional_relay_state_keys
+		.into_iter()
+		.filter(|key| !relevant_keys.contains(key))
+		.collect();
+	relevant_keys.extend(unique_keys);
+
 	relay_chain_interface
 		.prove_read(relay_parent, &relevant_keys)
 		.await
@@ -159,6 +167,7 @@ impl ParachainInherentDataProvider {
 		validation_data: &PersistedValidationData,
 		para_id: ParaId,
 		relay_parent_descendants: Vec<RelayHeader>,
+		additional_relay_state_keys: Vec<Vec<u8>>,
 	) -> Option<ParachainInherentData> {
 		// Only include next epoch authorities when the descendants include an epoch digest.
 		// Skip the first entry because this is the relay parent itself.
@@ -174,6 +183,7 @@ impl ParachainInherentDataProvider {
 			relay_parent,
 			!relay_parent_descendants.is_empty(),
 			include_next_authorities,
+			additional_relay_state_keys,
 		)
 		.await?;
 

prdoc/pr_9262.prdoc

@@ -0,0 +1,10 @@
+title: 'Adds support for additional relay state keys in parachain validation data inherent'
+doc:
+- audience: Node Dev
+  description: |-
+    Adds the possibility for parachain clients to collect additional relay state keys into the validation data inherent.
+crates:
+- name: cumulus-client-consensus-aura
+  bump: patch
+- name: cumulus-client-parachain-inherent
+  bump: major