Remove MMF support

[defagos]

Description

This PR removes MMF support in demo. Following recent changes made to our secret management the special associated endpoint was not visible in the demo app anyway. Moreover Android demo does not provide MMF support either, since we can always copy/paste the URLs to test in the demo directly.

Changes made

• Remove MMF endpoint.
• Make project configuration simpler by removing unnecessary xcconfig files. The build number is now bumped in the project itself.

Checklist

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