[IMP] website, website_forum: add a class modal_shown on modal once css animation is completed

Use this new class in website_forum to avoid that the tour click during
the animation and fail randomly.

https://getbootstrap.com/docs/4.0/components/modal/#events

addons/website/static/src/js/website.js

@@ -11,3 +11,13 @@ weContext.get = function (context) {
     }, weGetContext(context), context);
 };
 });
+
+odoo.define('website.website_modal', function (require) {
+'use strict';
+
+    require('web.dom_ready');
+
+    $('body').on('shown.bs.modal', function (e) {
+        $(e.target).addClass('modal_shown');
+    });
+});

addons/website_forum/static/src/js/website_tour_forum.js

@@ -51,6 +51,7 @@ odoo.define("website_forum.tour_forum", function (require) {
         content: _t("Click to post your question."),
         position: "bottom",
     }, {
+        extra_trigger: 'div.modal.modal_shown',
         trigger: ".modal-header button.close",
         auto: true,
     }, {
@@ -64,6 +65,7 @@ odoo.define("website_forum.tour_forum", function (require) {
         content: _t("Click to post your answer."),
         position: "bottom",
     }, {
+        extra_trigger: 'div.modal.modal_shown',
         trigger: ".modal-header button.close",
         auto: true,
     }, {