Accompany Notes Updating Sync Pkg to 3531

# Accompany Notes Updating Sync Pkg to 3531 Pre-req: https://github.com/ethereum/consensus-specs#3531 PR: https://github.com/prysmaticlabs/prysm/compare/update-sync ## Key Design Decisions and Open Questions ### First-Class Citizenship of ROBlob - Transitioned from using the protobuf format `ethpb.BlobSidecar` to `ROBlob`. - Benefits: Efficiently handles hash tree root headers. Enables caching of verification results. Open Question: Are there any downsides or limitations to making `ROBlob` a first-class citizen? ### Direct Alignment Check Using ROBlob and ROBlock - Utilizes `blob.Root()==block.Root()` for direct alignment checks. Benefits: Simplifies the verification process. ### Database Dependency in Sync Package Sync package depends on the DB package, which in turn affects other packages. Current State: Commented out DB-related code to prepare for the next PR. Which is ok, the feature is not ready for the 'develop' branch until all aspects are completed. Open Question: What is the most efficient way to manage these cross-package dependencies while updating the sync package? ## P2P Layer - Replace usage of `BlobSidecar` with `SignedBlobSidecar` in `BlobSubnetTopicFormat`. - Update `BroadcastBlob` to broadcast `SignedBlobSidecar`. - The existing proposer code will be modified to fulfill this; a **TODO** has been added for tracking. ## Gossip Layer - Receive `BlobSidecar` over the network, instead of `SignedBlobSidecar`. - Upon receipt, immediately convert `SignedBlobSidecar` to `ROBlob` to optimize header hash tree root calculations. - Apply `REJECT` label if conversion to `ROBlob` fails, as this indicates an incorrect blob sidecar format. `REJECT` makes more sense than `IGNORE` - Implement a direct getter for `RoBlock.Slot()`, `ParentRoot()`, `ProposerIndex()` to simplify calls. - Update `hasSeenBlobIndex` to take `slot, proposer_index, and index` as parameters, in line with spec updates. - Accept only the first valid sidecar for the tuple `(block_header.slot, block_header.proposer_index, blob_sidecar.index)`. ## RPC Layer - `SendBlobSidecarByRoot` and `SendBlobsByRangeRequest` will now return blobs in the new format. - Update `readChunkEncodedBlobs` and `fetchBlobsFromPeer` to use `ROBlob`. - Modify `verifyAndPopulateBlobs` to work with `ROBlob`. - Ensure `WriteBlobSidecarChunk` writes the updated blob sidecar format. ## Blob vs. Block Alignment check - Update `BlobAlignsWithBlock` function to use hash tree roots for comparison, thereby reducing verification steps like slot, and proposer index. Hash tree root of block and header should be the same. (Yay) - Design note: 1.) We need to inclusde blob and kzg commitments are valid. 2.) We also need to ensure the inclusion proofs are valid ## Database Handling - WARNING: I've commented out existing DB methods and add TODOs to update them for the new blob sidecar format. I'm not entirely sure if we want to do everything in one PR. Happy to do that though. ## Initial Sync - Revise `BlockWithVerifiedBlobs` to use `ROBlob`, thereby ensuring alignment between blocks and blobs. This is a very neat change imo. ## Chain Service - `ReceiveBlob` functionality will be updated once the DB methods like `SaveBlobSidecar` are revised.