Start-OpenTelemetryInvocationInternal can be called with empty TraceParent or TraceState - intended?

Discussion: Should we allow the Start-OpenTelemetryInvocationInternal cmdlet to be called when TraceParent is null or empty?
I do not know what scenario would cause this to happen. The TraceParent comes from the TraceContext in the InvocationRequest inside the worker. I assume it may be null/empty in the case when the host is not instrumented with any kind of telemetry, but in that case, not hooking up a host span would be the correct behavior.

Start by tracing how Start-OpenTelemetryInvocationInternal receives TraceParent and TraceState from the TraceContext in the InvocationRequest inside the worker. Determine the expected behavior when either value is null or empty, then verify that behavior with the relevant tests or document the decision if no test location is identified.

Written by the indexing model from the issue text.