NoOpTracer still sets up attributes when calling Span.updateAttributes

[adam-fowler]

When you call Span.updateAttributes(_:) on a NoOpSpan the included closure shouldn't be called. This is the cause of unexpected allocations when the tracer has been set to NoOp.

Is adding the function to the protocol a breaking change if you provide a default implementation?

Not calling the closure could be considered a breaking change I suppose given people might do other stuff inside that closure.

Ideally SpanAttributes would be an associatedtype and the NoOpSpan would have its own version that didn't do anything, but I think that ship may have sailed.