NewCommitteeChain creates a new CommitteeChain.

NewHeadTracker creates a new HeadTracker.

NewTestCommitteeChain creates a new CommitteeChain for testing.

CommitteeChain is a passive data structure that can validate, hold and update a chain of beacon light sync committees and updates.

HeadTracker keeps track of the latest validated head and the "prefetch" head which is the (not necessarily validated) head announced by the majority of servers.