Custom payload building

[adaki2004]

Please see if we can reuse this idea somehow. (There is a big printer function print_block_data, you can just ignore for now, it helped me debugging.)

Basically what i do is, i get a new (default) mutable payload (payload_clone) and in-place modifying the block body, txn list, recalculate hash, etc. in modify_payload_block().

(Note: I tried Optimism payload building, but the problem i saw with OptimismPayloadAttributes is , that it differs what we have now (EthPayloadBuilderAttributes)so we would need to adapt all the deps (node.rs, payload.rs, etc.))

[adaki2004]

Closing as done already on diff. branch.