RATIONALE Even will soon gain a major update called Event Online, allowing to better support full-online events. In order to prepare its merge, preparatory merge are done to lessen the final diff. PURPOSE Prepare Event Online support by providing fixes in registration and event frontend flows. Also provide a quick back2basic in backend views to prepare addition of Online sub modules. SPECIFICATIONS Be more explicit in search boxes: allow to set a placeholder. It helps users understanding purpose of the search tool. Set it to "Search an event ..." in website_event. LINKS Community PR odoo/odoo#55197 Enterprise PR odoo/enterprise#12113 Task ID-2309702 (Event Preparatory Merge 4) Prepares Task ID-2252655 (Main Online Event task) Prepares Task ID-2283796 (Event B2Basics / Registration Flow) Prepares Task ID-2299857 (Event Design Review) Co-Authored-By: Aurélien Warnon <awa@odoo.com> Co-Authored-By: David Beguin <dbe@odoo.com> Co-Authored-By: Thibault Delavallée <tde@odoo.com>