fsPromises.unlink(path)
如果 path 指向一个符号链接，则删除该链接而不影响该链接所指向的文件或目录。如果 path 指向一个非符号链接的文件路径，则删除该文件。更多详情请参阅 POSIX unlink(2) 文档。
【If path refers to a symbolic link, then the link is removed without affecting
the file or directory to which that link refers. If the path refers to a file
path that is not a symbolic link, the file is deleted. See the POSIX unlink(2)
documentation for more detail.】