graphman commands for analyzing and fixing bad block issues

Sometimes, we're missing transactions from blocks returned from Ethereum nodes.

Usually, we then have to manually

• compare the block in our database with the block returned from the Ethereum node,
• identify what subgraphs are or might be affected,
• roll them back or restart them.

This is tedious. It would be great to have graphman commands that do the following:

1. Given a network and block number or hash
   • Compare our cached block with the block on this network, identify all contract addresses of mismatching data in the block
   • Print a diff of the block
   • Print lists of all subgraphs that might be affected:
     • All subgraphs for this network that failed on that block
     • All subgraphs for this network that have
       • data sources for one of the contract addresses included in the mismatching block data
       • data sources with no contract address
2. Fix a block by refetching it from the network
3. Rewind / restart a list of subgraph deployments, if we don't have commands for this yet