Bump xmldom, react-native-fs and react-native-windows in /Example

Removes [xmldom](https://github.com/xmldom/xmldom). It's no longer used after updating ancestor dependencies [xmldom](https://github.com/xmldom/xmldom), [react-native-fs](https://github.com/itinance/react-native-fs) and [react-native-windows](https://github.com/microsoft/react-native-windows/tree/HEAD/vnext). These dependencies need to be updated together.


Removes `xmldom`

Updates `react-native-fs` from 2.16.6 to 2.20.0
- [Release notes](https://github.com/itinance/react-native-fs/releases)
- [Changelog](https://github.com/itinance/react-native-fs/blob/master/CHANGELOG.md)
- [Commits](https://github.com/itinance/react-native-fs/commits/v2.20.0)

Updates `react-native-windows` from 0.57.2 to 0.71.0
- [Release notes](https://github.com/microsoft/react-native-windows/releases)
- [Changelog](https://github.com/microsoft/react-native-windows/blob/react-native-windows_v0.71.0/vnext/CHANGELOG.md)
- [Commits](https://github.com/microsoft/react-native-windows/commits/react-native-windows_v0.71.0/vnext)

---
updated-dependencies:
- dependency-name: xmldom
  dependency-type: indirect
- dependency-name: react-native-fs
  dependency-type: direct:production
- dependency-name: react-native-windows
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]