Gateway Should Be Responsible For Making Sure Query Results Are Consistent Without Specifying Block

When querying for latest entities from a subgraph, one is not ensured a consistent response without specifying a block number or hash. This makes using this type of query that depends on up-to-date data at each block much more cumbersome, requiring the client to fetch the latest block number/hash from somewhere before sending off the query. Considering that polling for the latest data from a subgraph is likely a common use case, I believe the gateway itself should be responsible for populating the latest block number if no block is provided in the query.