Add parent trace context information when scheduling an orchestration

[bachuv]

These changes send trace context information (Activity.Current.Id) through the protobuf CreateInstanceRequest.ParentTraceContext field when scheduling a new orchestration instance to help correlate client and orchestrator functions for distributed tracing.

[philliphoff]

Also, while this will push the trace context to the backend, and the backend may pass back it back, for example, as part of an activity request, unless the SDK creates an ActivitySource and Activity using that context, worker activity won't be associated with the trace.

[jviau]

Also, while this will push the trace context to the backend, and the backend may pass back it back, for example, as part of an activity request, unless the SDK creates an ActivitySource and Activity using that context, worker activity won't be associated with the trace.

The DurableTask.Core SDK has all of the appropriate ActivitySource's implemented. This SDK will need it added though for customers using the AzureManaged backend.