update to latest light client libp2p protocol

[etan-status]

Incorporates the latest changes to the light client sync protocol based
on Devconnect AMS feedback. Note that this breaks compatibility with the
previous prototype, due to changes to data structures and endpoints.
See ethereum/consensus-specs#2802

Due to the amount of changes, it is best to review the heavily edited
files from scratch (likewise, for the spec).

[etan-status]

Tested this against the test cases in the consensus-specs repo, and also manually checked logs of local testnet to ensure the gossip is properly sent.

[github-actions]

Unit Test Results

     12 files  ±0     850 suites  +8   58m 20s ⏱️ + 4m 40s
1 693 tests ±0  1 645 ✔️ ±0    48 💤 ±0  0 ❌ ±0 
9 861 runs  +8  9 741 ✔️ ±0  120 💤 +8  0 ❌ ±0 

Results for commit 4395b19. ± Comparison against base commit 1e6b32b.

♻️ This comment has been updated with latest results.

[etan-status]

Ran CI tests 5 times, flakiness seems to be gone now. There was some randomness involved, in the way how we simulated sync committee signatures, where sometimes it would generate too many and would actually reach supermajority, breaking the test case assumption. This is now fixed by putting a cap on randomization to not exceed the supplied target participation percentage.

[tersec]

Linux i386 Nim 1.2:

[Suite] Light client [Preset: mainnet]
  [OK] Pre-Altair
    /home/runner/work/nimbus-eth2/nimbus-eth2/tests/test_light_client.nim(169, 29): Check failed: store.finalized_header == finalityUpdate.get.finalized_header
    store.finalized_header was (slot: 8192, proposer_index: 1, parent_root: fdedfe9932eb02cfb9380be5c86edfa03e54067726c084e6b29a440b16249233, state_root: f546a3f3e654a863614395ff7effdaf74850ddb3d23c6aa77ae54b7557efe74a, body_root: 2e0c9e75376f5dd11b4ba65c3688f265c84f7898fbc41908efc456856cdbfbff)
    finalityUpdate.get.finalized_header was (slot: 16384, proposer_index: 21, parent_root: 5d0d71a63d55c2ec04f148a2a57a9f9486b1906597b06fb01f9b0078f22bd869, state_root: 2d456114eb16f369a93b973d46ba2ff605f55dd45414afdc3c4f5375b98c398e, body_root: f8cdeb7bbb0e6061b17a21e7683ff124b13ab115265399c7ebe2c83a338b5376)
  [FAILED] Light client sync
  [OK] Init from checkpoint

[tersec]

https://ci.status.im/blue/organizations/jenkins/nimbus%2Fnimbus-eth2%2Fmultibranch/detail/PR-3623/19/pipeline/87 shows the same thing, even after 9bcc2b3:

[Suite] Light client [Preset: mainnet]
  [OK] Pre-Altair
    /Users/jenkins/workspace/_nimbus-eth2_multibranch_PR-3623/macos_arm64/tests/test_light_client.nim(169, 29): Check failed: store.finalized_header == finalityUpdate.get.finalized_header
    store.finalized_header was (slot: 8192, proposer_index: 1, parent_root: fbbf0fc9bd94b04c596782cb49853466858a607c7cf3d67a0dc92bc34d8047c4, state_root: f9a3981b961bf781b820603304da3554f7c1fd79d07c1a432b5f0c02c60b25cf, body_root: 99731a01c1c648a16454e1d6dc79335c1804f2f647ec394a99f98f5088f29895)
    finalityUpdate.get.finalized_header was (slot: 16384, proposer_index: 21, parent_root: 5bbfc1240f2524cf9c817541ac3b4256065050fed506c0b9ff8f0a266911c288, state_root: c64332da8ad60c7868de5dc26c2507ec560b205853829779be72b25a4faab54e, body_root: 792ac60a443e2052cc6f52067d480d273f2ed493bbf0661a9e3935a68dd09b7e)
  [FAILED] Light client sync
  [OK] Init from checkpoint

[arnetheduck]

this belongs in BeaconNode (which is where validator_duties keeps things for its own needs)

[etan-status]

Moved it into a separate pool type, as it is also used in gossip_validation (minus the Future). I think it's a nice compromise between having it in the block_pools_types_light_client where it clearly does not belong, and fragmenting these few vars across too many files.

[etan-status]

Manually validated against light client poc.