Track received candidate manifests per validator index

[EclesioMeloJunior]

Issue summary

We should track incoming manifests (Full or Acknowledgement) per ValidatorIndex and per CandidateHash

The manifest has a single type independent of its kind (Full or Acknowledgement):

// ManifestSummary represents a summary of a manifest being sent by a counterparty.
type ManifestSummary struct {
	// ClaimedParentHash is the claimed parent head data hash of the candidate.
	ClaimedParentHash Hash
	// ClaimedGroupIndex is the claimed group index assigned to the candidate.
	ClaimedGroupIndex GroupIndex
	// StatementKnowledge is a statement filter sent alongside the candidate, communicating knowledge.
	StatementKnowledge StatementFilter
}

This manifest are received from a remote peer and we should track it in a map using CandidateHash as its key

type ReceivedManifests struct {
    Received map[CandidateHash]ManifestSummary
    // seconded counts is a limit of how many seconded statement
    // a given candidate can have, defined per session
    SecondedCounts map[GroupIndex][]uint
}

Functionalities

• Import manifest summary:

  • To import the manifest summary in the map we should follow the conditions:

    • For new candidate hash we should check if the seconded in group respect the limit defined by the session, see statement-distribution/src/v2/mod.rs#L2414. This means that, the imported manifest should have the amount of seconded statements below the defined limit.
    • If the candidate already exists we can update it only if
      • the informations in the incoming manifest summary does not conflict with the current informations
      • the imported manifest should have the amount of seconded statements below the defined limit.

• Retrieve StatementKnowledge for a given candidate hash

Other information and links

• https://github.com/paritytech/polkadot-sdk/blob/3dc3a11cd68762c2e5feb0beba0b61f448c4fc92/polkadot/node/network/statement-distribution/src/v2/grid.rs#L732

Acceptance criteria

• New code is 60% covered with unit tests