* op-node: Add eth package changes

* op-node: Add testutils package

* op-node: Pull in L1/L2 source changes

* op-node: Make the refactor build

* Apply suggestions from code review

Use `NewPayloadErr` instead of `ForkchoiceUpdateErr` as pointed out by @protolambda
Co-authored-by: Diederik Loerakker <proto@protolambda.com>
Co-authored-by: Diederik Loerakker <proto@protolambda.com>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>