Add demo privacy manifest

[defagos]

Description

This PR adds a privacy manifest to the demo, fixing the following App Store Connect submission issue:

Changes made

Self-explanatory.

Checklist

• [x] APIs have been properly documented (if relevant).
• [x] The documentation has been updated (if relevant).
• [x] New unit tests have been written (if relevant).
• [x] The demo has been updated (if relevant).