[Feature] Add parentHash to _meta{block}

[Data-Nexus]

Description

In circumstances where consumers are polling for data each block, it's helpful to be able to identify if they're receiving state from an in-sequence block, or if the indexer identified a re-org and they should roll back blocks to get back in accord with the indexer.

Adding something like this would make this more graceful:

query {
  myEntity {
  id
  }
  _meta{
    block{
      number 
      hash 
      parentHash
  }
}

Are you aware of any blockers that must be resolved before implementing this feature? If so, which? Link to any relevant GitHub issues.

No response

Some information to help us out

• [ ] Tick this box if you plan on implementing this feature yourself.
• [X] I have searched the issue tracker to make sure this issue is not a duplicate.