Update append_to_webpack.config.js for 5.0

Author: adriendupuis

code_samples/back_office/search/append_to_webpack.config.js

@@ -1,4 +1,6 @@
-const ibexaConfigManager = require('./ibexa.webpack.config.manager.js');
+const ibexaConfigManager = require('@ibexa/frontend-config/webpack-config/manager');
+const getIbexaConfig = require('@ibexa/frontend-config/webpack-config/ibexa');
+const ibexaConfig = getIbexaConfig();
 
 ibexaConfigManager.add({
     ibexaConfig,