* fix REST liveness endpoint responding even when gossip is not enabled
* fix VC exit code on doppelganger hit
* fix activation epoch not being updated correctly on long deposit
queues
* fix activation epoch being set incorrectly when updating validator
* move most implementation logic to `validator_pool`, add tests
* ensure consistent logging between VC and BN
* add docs
Since the sync committee duties are no longer updated on every slot
and previously the sync committee aggregators selection proofs were
generated during the duties update, this now resulted in the client
using stale selection proofs (they must be generated at each slot).
The fix consists of moving the selection proof generation logic in
a different function which is properly executed on each slot.
Other changes:
* The logtrace tool has been enhanced with a framework for adding
new simpler log aggregation and analysis algorithms.
The default CI testnet simulation will now ensure that the blocks
in the network have reasonable sync committee participation.
* Fix doppelganger protection reorders validator indices in response issue.
* Add chronos metrics endpoint to nimbus REST API.
* Doppelganger protection now works on duties not on attestations.
Improve logging for doppelganger and indices.
* Improve doppelganger and indices logging.
* Add number of validators to logs.
* Move logging dumps from `debug` to `trace` level.
* Keymanager API for the validator client
* Properly treat the 'description' field as optional when loading Keystores
* Spec-compliant serialization of the slashing data in Keymanager's DeleteKeys response ()
Fixes#3940Fixes#3964Closes#3884 by adding test
Other changes:
* logtrace can now verify sync committee messages and contributions
* Many unnecessary use of pairs() have been removed for consistency
* Map 40x BN response codes to BeaconNodeStatus.Incompatible in the VC