Add "reason" parameter when terminating and resuming a Workflow

# Summary

Allow additional parameter when a workflow is terminated or resumed

## Use Cases

When a workflow is terminated by an external system, there is no indication on why it was terminated
Having some kind of additional data that could be show as an output parameter on the task where the workflow is suspended would enhance communication

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**Message from the maintainers**:

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Start by tracing the existing API entry points for terminating and resuming a Workflow, then follow how suspension and task output parameters are represented. Clarify how an external system supplies the reason and where it should appear when the workflow is suspended. Done means both operations accept the additional reason and the suspended task exposes it as output data.

Written by the indexing model from the issue text.