[FIX] website: restore edit menu dialog

Since saas-12.5, with recent ORM changes, writing on non-existing fields
does not trigger a warning anymore but instead crashes. This revealed
that the 12.0 "Edit Menu" dialog was doing some of that. Indeed,
depending on what was edited, we ended up writing on the 'is_homepage'
field, the 'text' field, the 'isNewWindow' field, ... which do not
exist.

This commit takes advantage of the fix to also lint the dialog code and
convert some of it to ES6.

Discovered while working on task-1925319

closes odoo/odoo#36204

Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>

addons/website/static/src/xml/website.contentMenu.xml

@@ -1,14 +1,14 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <templates id="template" xml:space="preserve">
 <t t-name="website.contentMenu.dialog.submenu">
-    <li t-att-data-menu-id="submenu.id">
+    <li t-att-data-menu-id="submenu.fields['id']">
         <div class="input-group">
             <div class="input-group-prepend">
                 <span class="input-group-text fa fa-bars" role="img" aria-label="Dropdown menu" title="Dropdown menu"/>
             </div>
             <span class="form-control d-flex align-items-center">
                 <span class="js_menu_label o_text_overflow flex-grow-1">
-                    <t t-esc="submenu.name"/>
+                    <t t-esc="submenu.fields['name']"/>
                 </span>
                 <i t-if="submenu.is_homepage" class="fa fa-home ml-3" role="img" aria-label="Home" title="Home"/>
             </span>