Add privacy manifest for iOS

[ueman]

Connection with issue(s)

Resolve issue #1909

This adds an empty privacy manifest. I could not find this library using any of the listed methods from https://developer.apple.com/documentation/bundleresources/privacy_manifest_files/describing_use_of_required_reason_api

This is similar to the changes seen in the first party Flutter plugins https://github.com/pichillilorenzo/flutter_inappwebview/issues/1909

Testing and Review Notes

I'm not really sure how to test this. I guess if this builds it's fine?

[mvolpato]

https://github.com/pichillilorenzo/flutter_inappwebview/pull/2028 5 minutes apart :)

[k-bacy]

#2028 5 minutes apart :)

when this pr can be confirmed

[acn-masatadakurihara]

@pichillilorenzo please confirme