Bug 1838208 - Part 2: Add opaqueResponseBlocking.mediaExceptionsStrategy to Nimbus. r=sefeng

Depends on D180926

Differential Revision: https://phabricator.services.mozilla.com/D180943

Author: farre

toolkit/components/nimbus/FeatureManifest.yaml

@@ -1598,6 +1598,11 @@ opaqueResponseBlocking:
       description: Whether filtering of internal responses in the parent ORB is enabled
       type: int
       setPref: "browser.opaqueResponseBlocking.filterFetchResponse"
+    mediaExceptionsStrategy:
+      description: >-
+        If we partially or wholly allow audio and video MIME types in conflict with spec.
+      type: int
+      setPref: "browser.opaqueResponseBlocking.mediaExceptionsStrategy"
 
 updatePrompt:
   description: Prefs to control content and behavior of update notifications