[feature] Add a request ID and include it in logs (#1476)

This adds a lightweight form of tracing to GTS. Each incoming request is
assigned a Request ID which we then pass on and log in all our log
lines. Any function that gets called downstream from an HTTP handler
should now emit a requestID=value pair whenever it logs something.

Co-authored-by: kim <grufwub@gmail.com>

internal/processing/fromclientapi.go

@@ -50,7 +50,7 @@ func (p *processor) ProcessFromClientAPI(ctx context.Context, clientMsg messages
 	}
 
 	// Log this federated message
-	l := log.WithFields(fields...)
+	l := log.WithContext(ctx).WithFields(fields...)
 	l.Info("processing from client")
 
 	switch clientMsg.APActivityType {