Port changes to `nextExchangeTransitionConfiguration` from BN to LC:
- 60 seconds delay before initial exchange
- 45 seconds interval between followup exchanges
- Only exchange post Bellatrix
When the sync queue processes results for a blocks by range request,
and the requested range contained some slots that are already finalized,
`BlockError.MissingParent` currently leads to `PeerScoreBadBlocks` even
when the error occurs on a non-finalized slot in the requested range.
This patch changes the scoring in that case to `PeerScoreMissingBlocks`
for consistency with range requests solely covering non-finalized slots,
and, likewise, rewinds the sync queue to the next `rewindSlot`.
Per spec, we should not be sending our detected terminal block to EL -
the EL configuration exchange should only look at values from
configuration and report mismatches.
`p.dataProvider` may become `nil` between individual attempts to
exchange transition configuration with the EL. Harden by capturing
the data provider on function start.
Note that other functions are already hardened, or are unaffected.
Only `close` transitions `p.dataProvider` to `nil`, and `close` is
only called by the main deposits import sequence. During the deposits
import, `close` is not called, so extra checks are not needed.
When there are a lot of deposits, we decompress the public key into a
crypto cache. To avoid having those caches grow unreasonably big,
make sure to operate on the decompressed pubkey instead.
* more efficient forkchoiceUpdated usage
* await rather than asyncSpawn; ensure head update before dag.updateHead
* use action tracker rather than attached validators to check for next slot proposal; use wall slot + 1 rather than state slot + 1 to correctly check when missing blocks
* re-add two-fcU case for when newPayload not VALID
* check dynamicFeeRecipientsStore for potential proposal
* remove duplicate checks for whether next proposer
`news` has a few open issues that are not present in `nim-websock`:
1. There is a 1 second delay between each MB of sent data.
2. Cancelling an ongoing `send` makes the entire WebSocket unusable.
3. Control packets do not have priority over ongoing message frames.
Using `news`, there are quite a few of these messages in Geth:
```
Previously seen beacon client is offline. Please ensure it is
operational to follow the chain!
```
It may take quite some time to reconnect when this happens.
Using `nim-websock`, this message still occurs because `eth1_monitor`
reconnects the EL connection when no new blocks occurred for 5 minutes,
but reconnecting is quick and the message is rarer.
The sync protocol does not distinguish between:
- All requested slots are empty
- Peer does not have data available about requested range
Therefore, we treat EOF for `beacon_blocks_by_range` and for
`beacon_blocks_by_range` as valid responses, as if the entire epoch
really contained no single block for any slot. Once a followup response
provides new blocks, we detect that some blocks were missing and rewind.
During backfill, we also request the known-to-exist `backfill.slot`,
so we can actually detect whether an epoch really does not have blocks
or whether a response is incomplete (`PeerScoreNoBlocks`).