fix(csp): allow images from prod (developer.mozilla.org) (#12514)

Otherwise we cannot load `apple-touch-icon` and `favicon` on other hosts, including localhost.

Author: caugner

libs/constants/index.js

@@ -155,6 +155,7 @@ export const CSP_DIRECTIVES = {
     "profile.stage.mozaws.net",
     "profile.accounts.firefox.com",
 
+    "developer.mozilla.org",
     "mdn.dev",
     "interactive-examples.mdn.mozilla.net",
     "interactive-examples.mdn.allizom.net",