* Initial commit.
* NextAttestationEntry type.
* Add doppelgangerCheck and actual check.
* Recover deleted check.
* Remove NextAttestainEntry changes.
* More cleanups for NextAttestationEntry.
* Address review comments.
* Remove GENESIS_EPOCH specific check branch.
* Decrease number of full epochs for doppelganger check in VC.
Co-authored-by: zah <zahary@status.im>
Eugene Kabanov