This PR adds support for ArrowGlacier, as defined by

    https://github.com/ethereum/execution-specs/blob/master/network-upgrades/mainnet-upgrades/arrow-glacier.md
    https://eips.ethereum.org/EIPS/eip-4345

> Starting with FORK_BLOCK_NUMBER the client will calculate the difficulty based on a fake block number suggesting to the client that the difficulty bomb is adjusting 10,700,000 blocks later than the actual block number.

This also adds support for evm t8n to return the calculated difficulty, so it can be used to construct test.