Allow screen capture without prior user gesture

For security reasons, the getDisplayMedia() web API requires a prior user gesture ("transient activation") to be called or will otherwise fail. With this policy set, admins can specify origins on which this API can be called without prior user gesture. For detailed information on valid url patterns, please see https://chromeenterprise.google/policies/url-patterns/. * is not an accepted value for this policy. If this policy is unset, all origins will require a prior user gesture to call this API. Example value: https://www.example.com [*.]example.edu