Do not write repeated workflow task heartbeat to the history

[mfateev]

Is your feature request related to a problem? Please describe. A very long running local activity can lead to many repeated WorkflowTaskCompleted/Scheduled/Started events written to the history.

Describe the solution you'd like Do not write these events if there are no commands included in WorkflowTaskCompleted and there are no new events.

We already do a similar "deduping" when processing constantly failing/timing out workflow tasks.