Implement aggregation in pipeline service

[mirgee]

Currently BlockAccessListDataRequest#doPersist is called for each batch of responses corresponding to the batched BAL request GetBlockAccessListsMessage.

Instead of committing those changes for each batch, this PR adds an aggregation pipe to the pipeline, which aggregates all the batches into a single list and commits the corresponding changes to the flat database in one atomic operation. This allows us to compare state of each account in the BALs with the account trie (which by that point is already healed).

TODO:

• It is possible to avoid unchecked casts and rely on compile-time type safety by making inSingleBatch available only on PipelineBuilders with pipeEnd being a ReadPipe<List<T>> (e,g, those created by inBatches), but it might require a more invasive change. We will do this later