Add a custom class in web_editor to prevent the selection in an embedded view (or another bloc using that class) from being moved out in multiple situations. (onselectionchange, onkeyup, onmouseup, ...). This is related to the block being contentEditable=False. Prepares Task-2796156 Prepares odoo/enterprise#29423 X-original-commit: 86c14110294c5ff986ee88bb010dbc7513bf8b01 Part-of: odoo/odoo#101694