Block -> Tree Shaking: Separate Consensus Methods

[holgerd77]

Sorry, I am still not willing to fully throw Ethash and Clique out. 🫣 😆 What we can do though is to (easily) further separate.

For Block the consensus related methods should go into separate methods additionally taking in the block object as a first parameter being placed into:

• consensus/ethash.ts
• consensus/clique.ts
• consensus/index.ts (for export as usual, all methods should also be available from root)

Following methods:

• ethashCanonicalDifficulty()
• _requireClique() (should also go out from Block and used with additional block parameter from the new location, but not being exposed to users)
• cliqueSigHash()
• cliqueIsEpochTransition()
• cliqueExtraVanity()
• cliqueExtraSeal()
• NOT cliqueSealBlock() (separate topic, at least not for this round of work (bound to a constructor option, at least substantially more difficult to substitute/move/replace))
• cliqueEpochTransitionSigners()
• cliqueVerifySignature()
• cliqueSigner()

I would cautiously think we can just keep the method names.

If there are method checks like if Block.ethashCanonicalDifficulty !== undefined in the code base these checks can be removed.

Bundle size for a block example before/after should be provided especially on this one since this should be pretty satisfactory! 😂