Resolves to the absolute normalized path, with symbolic links resolved.

  // e.g. given /home/alice/file.txt and current directory /home/alice
  await Deno.symlink("file.txt", "symlink_file.txt");
  const realPath = await Deno.realPath("./file.txt");
  const realSymLinkPath = await Deno.realPath("./symlink_file.txt");
  console.log(realPath);  // outputs "/home/alice/file.txt"
  console.log(realSymLinkPath);  // outputs "/home/alice/file.txt"

Requires allow-read permission.