feat(storage): support a object storage custom path prefix

models/s3Storage.go

@@ -11,6 +11,9 @@ type S3 struct {
 	ACL            string `json:"acl,omitempty"`
 	ForcePathStyle bool   `json:"forcePathStyle"`
 
+	// PathPrefix is an optional prefix for object storage.
+	PathPrefix string `json:"pathPrefix,omitempty"`
+
 	// This property is no longer used as of v0.1.1. See the standalone
 	// property that was pulled out of here instead. It's only left here
 	// to allow the migration to take place without data loss.