Tracing Context for Service from Trace

All the methods I can find currently take explicit Spans. Which I assume comes from assumptions about how `Trace` is implemented. But in natchez `Trace` is the core construct and `Kleisli[F, Span[F], *]` is one instance of how to get a `Trace` would be nice if we could use `implicit T: Trace[F]` to automatically get a Traced Service in `F`