[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/storage/storage.go

@@ -128,8 +128,9 @@ func NewFileStorage() (*Driver, error) {
 		return nil, fmt.Errorf("error opening disk storage: %w", err)
 	}
 
+	// Perform an initial storage clean to delete old dirs.
 	if err := disk.Clean(context.Background()); err != nil {
-		log.Errorf("error performing storage cleanup: %v", err)
+		log.Errorf(nil, "error performing storage cleanup: %v", err)
 	}
 
 	return &Driver{