Modify: add general ReaderCloserSeeker interface for handler GET method to return

pkg/filesystem/response/common.go

@@ -10,3 +10,9 @@ type ContentResponse struct {
 	Content  io.ReadSeeker
 	URL      string
 }
+
+// 存储策略适配器返回的文件流，有些策略需要带有Closer
+type RSCloser interface {
+	io.ReadSeeker
+	io.Closer
+}