iOS: Add associated domain to improve UX with password managers

[mschoettle]

When using a password manager it is not possible to easily auto-fill the credentials because the app does not have an associated domain. So the credentials cannot be proposed based on that.

Note that there is also a review feedback by a user in the app store based on this.

• https://developer.apple.com/documentation/xcode/supporting-associated-domains
• https://stackoverflow.com/questions/70019294/universal-links-cordova-ios-application
• Potentially useful: https://www.npmjs.com/package/cordova-plugin-app-scope