Function allow_write_implicit_dir_over_file

cpp/src/arrow/filesystem/test_util.h:172–172

- Whether the filesystem may allow writing a directory "over" a file, for example copying file "A" to "B/C" while "B" exists and is a file.

  // - Whether the filesystem may allow writing a directory "over" a file,
  //   for example copying file "A" to "B/C" while "B" exists and is a file.
  virtual bool allow_write_implicit_dir_over_file() const { return false; }
  // - Whether the filesystem allows reading a directory
  virtual bool allow_read_dir_as_file() const { return false; }
  // - Whether the filesystem allows moving a file