Control referrer information access for permissive referrer policy

This policy determines how websites can access referrer information when a very permissive referrer policy is specified (i.e., "unsafe-url"). If this policy is set to 1 (AllowPermissiveReferrerPolicy), permissive referrer policies are allowed (i.e., "unsafe-url" requests contain the full URL of the referrer). If this policy is set to 2 (CapToStrictReferrerPolicy), referrer values are capped to "strict-origin-when-cross-origin" policy, so cross-origin requests contain only the origin of the referrer or no referrer if downgraded from HTTPS to HTTP. Same-origin requests contain the full URL of the referrer. If left unset, referrer values are capped to "strict-origin-when-cross-origin" policy by default, but users can modify this by: - changing the cookie control in the Shields panel to "Allow all cookies" - disabling Shields on a specific site