feat: support querying block data in transaction schema

[luciorubeens]

This PR improves the transaction model by introducing a block resolver, allowing transactions to be queried along with their associated block data. This is useful for retrieving details like the block timestamp without requiring separate queries.

Usage example:

query {
  getTransactions(
    where: {
      hash: { eq: "u/KxH6JkCktJARpBn5nrYHJs91cLSREqZLKJUbgYFf8=" }
    }
  ) {
    hash
    block_height
    block {
      time
    }
  }
}

[ajnavarro]

Seems reasonable.

WDYT about deprecating block_height on the Transactions model? to keep the API consistent. It can still be used internally for doing the Block query, but I would rather not expose it and if the user needs the data, they can get it through the block object if required.

Should we do the same when retrieving blocks? WDYT?