[REF] website, *: use public widgets instead of website animations

* website_blog, website_crm_partner_assign, website_event,
  website_event_track, website_form, website_forum, website_links,
  website_mail, website_mail_channel, website_mass_mailing,
  website_sale, website_sale_comparison, website_sale_delivery,
  website_sale_stock, website_sale_wishlist, website_slides,
  website_twitter

While using the 'Animation' class of website instead of the frontend
'Widget' class leads to the same behaviors, this refactoring is done for
two reasons:
- Stop using the confusing 'Animation' name for non-animated behaviors
- Instantiation of 'Widget' is slightly faster than 'Animation'

Part of https://github.com/odoo/odoo/pull/29442
task-1932066

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

@@ -10,9 +10,9 @@ odoo.define('website.user_custom_code', function (require) {
 'use strict';
 
 var Dialog = require('web.Dialog');
-var sAnimations = require('website.content.snippets.animation');
+var publicWidget = require('web.public.widget');
 
-sAnimations.registry.HelloWorldPopup = sAnimations.Class.extend({
+publicWidget.registry.HelloWorldPopup = publicWidget.Widget.extend({
     selector: '#wrapwrap',
 
     start: function () {