Track fork diff

[Suning Yao]

For many L2 Rollups, they have forked the client from geth, so they show the following diff via an explorer.

• https://op-geth.optimism.io/
• https://geth.taiko.xyz/

In addition, there are similar projects that show EVM diff or other generic diffs.

• evm-diff
• forkdiff

Since this repo is built on graph-ts, and aims for Subgraph-equivalence, it needs a similar presentation.