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 the API
fails.

When this policy is configured, admins can specify origins on which this API
can be called without prior user gesture.

For detailed information on valid url patterns, see
https://go.microsoft.com/fwlink/?linkid=2095322. Note: * isn't an accepted
value for this policy.

If this policy isn't configured, all origins require a prior user gesture to
call this API.

Example value:

https://www.example.com
[*.]example.edu