improved plugin class by changing for only one method to do all

plugins/fipfcard_plugin/js/example_init.js

@@ -1,6 +1,8 @@
+console.log("PLGNTLS_data:");
+console.log(PLGNTLS_data);
 
 const title = document.querySelector(".first_el_to_change");
-title.innerHTML = "--- coucou ;) " + myvar_1;
+title.innerHTML = "--- coucou ;) " + PLGNTLS_data.myvar_1;
 
 const ajax_button_1 = document.querySelector("#test_ajax_1");
 ajax_button_1.addEventListener('click', () => {