feat: add upyun-uss driver

drivers/uss/util.go

@@ -0,0 +1,13 @@
+package uss
+
+import "strings"
+
+// do others that not defined in Driver interface
+
+func getKey(path string, dir bool) string {
+	path = strings.TrimPrefix(path, "/")
+	if dir {
+		path += "/"
+	}
+	return path
+}