feat(web): make google cast opt in (#18514)

* add setting switch

this isnt bound to anything yet

* make google casting opt-in

* doc updates

* lint docs

* remove unneeded translation items

* update mobile openai defs

* fix failing test

we need to mock user prefs since CastButton uses it

server/src/utils/preferences.ts

@@ -42,6 +42,9 @@ const getDefaultPreferences = (): UserPreferences => {
       showSupportBadge: true,
       hideBuyButtonUntil: new Date(2022, 1, 12).toISOString(),
     },
+    cast: {
+      gCastEnabled: false,
+    },
   };
 };