[fenix] For issue https://github.com/mozilla-mobile/fenix/issues/18132 create feature flag for refreshing icons

app/src/main/java/org/mozilla/fenix/FeatureFlags.kt

@@ -43,4 +43,9 @@ object FeatureFlags {
      * Enables the tabs tray re-write with Synced Tabs.
      */
     val tabsTrayRewrite = Config.channel.isNightlyOrDebug
+
+    /**
+     * Enables the updated icon set look and feel.
+     */
+    val newIconSet = Config.channel.isNightlyOrDebug
 }