api: add skip_randao_verification for produceBlockV2

[michaelsproul]

Implement ethereum/beacon-APIs#222.

If my Nim isn't too atrocious hopefully I might be able to get this to a mergeable state. I'm putting it up as a draft for gentle feedback (this is my first time ever writing Nim).

Does the broad angle of attack seem acceptable? My next step would be to work out how to put a zero randao_reveal in when none is provided, and to add a new UpdateFlag to disable verification of the RANDAO signature only.

[github-actions]

Unit Test Results

       12 files  ±0       860 suites  ±0   1h 14m 13s ⏱️ + 4m 6s
  1 982 tests ±0    1 835 ✔️ ±0  147 💤 ±0  0 ❌ ±0 
10 662 runs  ±0  10 472 ✔️ ±0  190 💤 ±0  0 ❌ ±0 

Results for commit 9e22583. ± Comparison against base commit 80f44f4.

♻️ This comment has been updated with latest results.

[arnetheduck]

this is my first time ever writing Nim

welcome to the bright side - fortunately, it's not that easy to write atrocious Nim code (which perhaps is the main raison d'etre of it), and yours is already looking quite good ;)

I guess there are two things to look at here: is the PR good, and is the feature desired in general - I'll focus on the former and then we can have the latter discussion in the spec PR, upon which this PR would depend :)

[arnetheduck]

@michaelsproul since ethereum/beacon-APIs#222 is merged, we can go ahead with this PR as well as soon as it's rebased / updated to the new param names etc

[michaelsproul]

I've updated this PR to use the skip_randao_verification flag that was decided upon in the beacon-APIs repo. I've tested it manually and it seems to be working well. If you'd like me to add some automated tests please point me in the right direction.

[arnetheduck]

If you'd like me to add some automated tests please point me in the right direction.

The relevant location is here:

nimbus-eth2/tests/testblockutil.nim

Line 99 in 2ad5239

randao_reveal =

: we need to teach this function to take a valid/invalid randao and pass on the new randao flag, then teach

nimbus-eth2/tests/test_blockchain_dag.nim

Line 30 in 2ad5239

suite "Block pool processing" & preset():

to call it with the various combinations - although the suite creates some dummy blocks, a new test in it will do fine.

[arnetheduck]

Thanks for the feature and the upstream spec! I'll merge this now and throw in some tests in a separate PR.

[michaelsproul]

Thanks for having me on as a novice Nimbus contributor! I'll wear the badge with pride 😁