Add Feature-Policy header

The header has been renamed to Permissions-Policy, but Rails has no support so far.

config/initializers/permissions_policy.rb

@@ -1,12 +1,26 @@
 # frozen_string_literal: true
+
 # Define an application-wide HTTP permissions policy. For further
 # information see https://developers.google.com/web/updates/2018/06/feature-policy
-#
-# Rails.application.config.permissions_policy do |f|
-#   f.camera      :none
-#   f.gyroscope   :none
-#   f.microphone  :none
-#   f.usb         :none
-#   f.fullscreen  :self
-#   f.payment     :self, "https://secure.example.com"
-# end
+# TODO: Feature-Policy has been renamed to Permissions-Policy. The Permissions-Policy is
+#       not yet supported by Rails (even though the new name is already used for the method)
+Rails.application.config.permissions_policy do |policy|
+  policy.accelerometer        :none
+  policy.ambient_light_sensor :none
+  policy.autoplay             :none
+  policy.camera               :none
+  policy.encrypted_media      :none
+  policy.fullscreen           :none
+  policy.geolocation          :none
+  policy.gyroscope            :none
+  policy.magnetometer         :none
+  policy.microphone           :none
+  policy.midi                 :none
+  policy.payment              :none
+  policy.picture_in_picture   :none
+  # The `speaker` directive is used for selection of non-default audio output devices
+  policy.speaker              :none
+  policy.usb                  :none
+  policy.vibrate              :none
+  policy.vr                   :none
+end