Rework Validator Client fallback mechanism (#4393)

* Rework Validator Client fallback mechanism

* Add CI workflow for fallback simulator

* Tie-break with sync distance for non-synced nodes

* Fix simulator

* Cleanup unused code

* More improvements

* Add IsOptimistic enum for readability

* Use configurable sync distance tiers

* Fix tests

* Combine status and health and improve logging

* Fix nodes not being marked as available

* Fix simulator

* Fix tests again

* Increase fallback simulator tolerance

* Add http api endpoint

* Fix todos and tests

* Update simulator

* Merge branch 'unstable' into vc-fallback

* Add suggestions

* Add id to ui endpoint

* Remove unnecessary clones

* Formatting

* Merge branch 'unstable' into vc-fallback

* Merge branch 'unstable' into vc-fallback

* Fix flag tests

* Merge branch 'unstable' into vc-fallback

* Merge branch 'unstable' into vc-fallback

* Fix conflicts

* Merge branch 'unstable' into vc-fallback

* Remove unnecessary pubs

* Simplify `compute_distance_tier` and reduce notifier awaits

* Use the more descriptive `user_index` instead of `id`

* Combine sync distance tolerance flags into one

* Merge branch 'unstable' into vc-fallback

* Merge branch 'unstable' into vc-fallback

* wip

* Use new simulator from unstable

* Fix cli text

* Remove leftover files

* Remove old commented code

* Merge branch 'unstable' into vc-fallback

* Update cli text

* Silence candidate errors when pre-genesis

* Merge branch 'unstable' into vc-fallback

* Merge branch 'unstable' into vc-fallback

* Retry on failure

* Merge branch 'unstable' into vc-fallback

* Merge branch 'unstable' into vc-fallback

* Remove disable_run_on_all

* Remove unused error variant

* Fix out of date comment

* Merge branch 'unstable' into vc-fallback

* Remove unnecessary as_u64

* Remove more out of date comments

* Use tokio RwLock and remove parking_lot

* Merge branch 'unstable' into vc-fallback

* Formatting

* Ensure nodes are still added to total when not available

* Allow VC to detect when BN comes online

* Fix ui endpoint

* Don't have block_service as an Option

* Merge branch 'unstable' into vc-fallback

* Clean up lifetimes and futures

* Revert "Don't have block_service as an Option"

This reverts commit b5445a09e9.

* Merge branch 'unstable' into vc-fallback

* Merge branch 'unstable' into vc-fallback

* Improve rwlock sanitation using clones

* Merge branch 'unstable' into vc-fallback

* Drop read lock immediately by cloning the vec.

Cargo.lock

@@ -2535,6 +2535,7 @@ version = "0.1.0"
 dependencies = [
  "account_utils",
  "bytes",
+ "derivative",
  "eth2_keystore",
  "ethereum_serde_utils",
  "ethereum_ssz",