Track actual cookie value so when implementing a hybrid consent screen where you first disable cookies and then enable cookies if consent given, then no new visitor is being created. If user doesn't give consent, then cookies stay disabled.
Setting actual cookie value is important because we include whether the user has cookies or not in the fingerprint: https://github.com/matomo-org/matomo/blob/3.13.6/core/Tracker/Settings.php#L145 . disableCookies / enableCookies otherwise creates a different fingerprint.
Creating this as part of 3.x since this is rather "urgently" needed as nowadays this behaviour is often wanted/needed and already used by various users.