Deprecate flags for ethash mining

[rjl493456442]

There are a few CLI flags for ethash mining. Since ethereum is already switched to PoS, these flags should be deprecated.

• miner.threads
• miner.notify
• miner.notify.full
• miner.etherbase
• miner.extradata
• miner.noverify

[karalabe]

I started working on a PR to remove ethash altogether. It's a bit of a larger refactor because I need to create a noop consensus engine for tests / chain makers / etc. Will include the removal of these flags too

[rjl493456442]

But ethash is still needed in case we want to run full sync? Legacy consensus validation.

[karalabe]

Mainnet was flipped over to be post-merge, meaning it always requires a beacon client sethead, even on initial genesis sync. At that point, we don't need to verify PoW any more, we just assume the security of the consensus client and run whatever it gives us. This permits us to get rid of ethash altogether.

After stopping Rinkeby, we'll also be able to get rid of Clique, and thus completely wiping the consensus package and related complexity. This would also allow us to get back to having a single entry point for inserting new blocks / reorging the chain into the system. One extra needed is to have a Clique v2 that operates above the engine API.

[rjl493456442]

Does it mean we can also get rid of the block generation logic in miner package? If so we only need to keep the logic for generating payload by demand. It should simplify the codebase a lot.

But yeah, if we deprecate the entire consensus package, it means we not are a complete client at all and it might be problematic for dev network? (we can't launch a network by ourselves).

[s1na]

Fixed via #27178