Allows you to set whether websites are allowed to use the Idle Detection API.
When this policy is set to 1 - AllowIdleDetection, websites can use the API without asking the user for permission.
When this policy is set to 2 - BlockIdleDetection, websites can't use the API, regardless of the user's permission.
When this policy is set to 3 - AskIdleDetection or not set, websites can't use the API without the user's permission.