* Convert genesis times from seconds to time.Time
* Fixing failed forkchoice tests in a new commit so it doesn't get worse
Fixing failed spectest tests in a new commit so it doesn't get worse
Fixing forkchoice tests, then spectests
* Fixing forkchoice tests, then spectests. Now asking for help...
* Fix TestForkChoice_GetProposerHead
* Fix broken build
* Resolve TODO(preston) items
* Changelog fragment
* Resolve TODO(preston) items again
* Resolve lint issues
* Use consistant field names for sinceSlotStart (no spaces)
* Manu's feedback
* Renamed StartTime -> UnsafeStartTime, marked as deprecated because it doesn't handle overflow scenarios.
Renamed SlotTime -> StartTime
Renamed SlotAt -> At
Handled the error in cases where StartTime was used.
@james-prysm feedback
* Revert beacon-chain/blockchain/receive_block_test.go from 1b7844de
* Fixing issues after rebase
* Accepted suggestions from @potuz
* Remove CanonicalHeadSlot from merge conflicts
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Co-authored-by: potuz <potuz@prysmaticlabs.com>
