Api to work with IBeaconStateView

[twoeths]

Problem description

as per #8650 we will not have full beacon state after we consume lodestar-z state-transition

Solution description

switch to using IBeaconStateView for all apis, enhance IBeaconStateView if needed
we should also avoid using EpochCache api, for example getIndexedSyncCommitteeAtEpoch

Additional context

No response