Move erasure root out of candidate commitments and into descriptor (#2010)

* guide: move erasure-root to candidate descriptor

* primitives: move erasure root to descriptor

* guide: unify candidate commitments and validation outputs

* primitives: unify validation outputs and candidate commitments

* parachains-runtime: fix fallout

* runtimes: fix fallout

* collation generation: fix fallout

* fix stray reference in primitives

* fix fallout in node-primitives

* fix remaining fallout in collation generation

* fix fallout in candidate validation

* fix fallout in runtime API subsystem

* fix fallout in subsystem messages

* fix fallout in candidate backing

* fix fallout in availability distribution

* don't clone

* clone

Co-authored-by: Sergei Shulepov <sergei@parity.io>

polkadot/roadmap/implementers-guide/src/types/candidate.md

@@ -80,6 +80,8 @@ struct CandidateDescriptor {
 	persisted_validation_data_hash: Hash,
 	/// The blake2-256 hash of the pov-block.
 	pov_hash: Hash,
+	/// The root of a block's erasure encoding Merkle tree.
+	erasure_root: Hash,
 	/// Signature on blake2-256 of components of this receipt:
 	/// The parachain index, the relay parent, the validation data hash, and the pov_hash.
 	signature: CollatorSignature,
@@ -251,8 +253,6 @@ struct CandidateCommitments {
 	horizontal_messages: Vec<OutboundHrmpMessage>,
 	/// Messages destined to be interpreted by the Relay chain itself.
 	upward_messages: Vec<UpwardMessage>,
-	/// The root of a block's erasure encoding Merkle tree.
-	erasure_root: Hash,
 	/// New validation code.
 	new_validation_code: Option<ValidationCode>,
 	/// The head-data produced as a result of execution.
@@ -275,27 +275,4 @@ struct SigningContext {
 	/// The session index this signature is in the context of.
 	session_index: SessionIndex,
 }
-```
-
-## Validation Outputs
-
-This struct encapsulates the outputs of candidate validation.
-
-```rust
-struct ValidationOutputs {
-	/// The head-data produced by validation.
-	head_data: HeadData,
-	/// The validation data, persisted.
-	validation_data: PersistedValidationData,
-	/// Messages directed to other paras routed via the relay chain.
-	horizontal_messages: Vec<OutboundHrmpMessage>,
-	/// Upwards messages to the relay chain.
-	upwards_messages: Vec<UpwardsMessage>,
-	/// The new validation code submitted by the execution, if any.
-	new_validation_code: Option<ValidationCode>,
-	/// The number of messages processed from the DMQ.
-	processed_downward_messages: u32,
-	/// The mark which specifies the block number up to which all inbound HRMP messages are processed.
-	hrmp_watermark: BlockNumber,
-}
-```
+```

polkadot/roadmap/implementers-guide/src/types/overseer-protocol.md

@@ -503,7 +503,7 @@ Various modules request that the [Candidate Validation subsystem](../node/utilit
 enum ValidationResult {
 	/// Candidate is valid, and here are the outputs and the validation data used to form inputs.
 	/// In practice, this should be a shared type so that validation caching can be done.
-	Valid(ValidationOutputs, PersistedValidationData),
+	Valid(CandidateCommitments, PersistedValidationData),
 	/// Candidate is invalid.
 	Invalid,
 }