fix: StatResult ctime type

[n-kulic]

This pull request fixes ctime type which is, in fact, a Date value, as evidenced in the stat implementation method:

• https://github.com/itinance/react-native-fs/blob/master/FS.common.js#L306C17-L306C17

type StatResult = {
  name: ?string;
  path: string;
  size: string;
  mode: number;
  ctime: number; // <-- Invalid type as shown in below stat method
};

// ...

stat(filepath: string): Promise<StatResult> {
  return RNFSManager.stat(normalizeFilePath(filepath)).then((result) => {
    return {
      'path': filepath,
      'ctime': new Date(result.ctime * 1000), // <-- ctime is a Date type, not a number
      ...
    };
  });
}