Deduplicate `mainnet_blocks_from_rpc` and `optimism_mainnet_blocks_from_rpc`

[hai-rise]

We can share the main flow of fetching block, setting up an RPC storage and running test_execute_alloy. Each chain can just pass in the difference like chain, rpc_url, and block numbers.

[varun-doshi]

I'd like to take this up

[hai-rise]

@varun-doshi Assigned, thank you!

[MuhtasimTanmoy]

Is this project active?

[hai-rise]

@MuhtasimTanmoy Unfortunately we have deemed other features (shreds, better state access, etc.) more valuable to end users so there hasn't been meaningful development since last October. We'll likely make a comeback by the end of the year when execution becomes a bottleneck again though 🙏.

[hai-rise]

Done in #475.