Most of the necessary testing for SERVER-40078 is accomplished as part of the patch for that ticket. As part of SERVER-40659, add the following unit tests:

• Ensure ReplicationCoordinatorImpl's replSetUpdatePosition successfully propagates applied and durable wall clock time information
• Ensure TopologyCoordinator's updateLastCommittedOpTimeAndWallTime only uses OpTime chronology (as opposed to also using wall clock time chronology) to update the commit point