Properly treat activity/child cancellation errors bubbled as workflow cancel

[cretz]

Describe the bug

Workflow cancellation not reported as such when bubbling the activity cancellation. TypeScript properly converts activity error and child workflow error that are caused by cancellation into workflow cancellation when a cancellation is requested. We need to do the same.

Technically it means that if a user wraps the error the workflow will show as failed not cancelled, but there's not much we can do about that.