* Changes to support injection of ShardSyncer, LeaseTaker, and LeaseRenewer into KCL Worker
* Additional checks around injection of LeaseRenewer and LeaseRenewerThreadPool
* Changed accessor on InitialPositionInStreamExtended to public to allow ShardSyncer injection
* Changed ShardSyncer to a public interface. Renamed implementation to KinesisShardSyncer.
* Removed wild card imports introduced in previous commit
* Minor refactoring in Worker Builder
* Added license info to ShardSyncer interface. Minor refactoring
* Changes to chain constructor in LeaseCoordinator
* Changed accessor on InitialPositionInStreamExtended factory methods. Minor changes in Worker builder.
* Changes to support periodic shard sync
* Patching changes left out in merge
* Overriding shard-sync idle time to 0 for periodic shard-sync
* Addressed PR feedback
* Addresed PR #579 review comments
* Modified constructor for DeterministicShuffleShardSyncLeaderDecider
* Addressed PR comments
* Fixed failing test
* Removed redundant member varible
* Re-enable metrics for shard-sync
* Removed unused method from ShardSyncTaskManager
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