Control first-party storage retention behavior

This policy determines whether Brave remembers or forgets first-party storage data when users close tabs or navigate away. If this policy is set to 1 (RememberFirstPartyStorage), first-party storage data is preserved across sessions. If this policy is set to 2 (ForgetFirstPartyStorage), first-party storage data is cleared when tabs are closed or users navigate away. If left unset, Brave preserves first-party storage data across sessions by default, but users can modify this through Brave Shields settings.