Closes #16367 opw-728387
Commit 3c9e6c89e7207636c1bdab4ed8118c0c1089d43e made big changes to the link editor dialog... but also broke many features with it. Commit 9a1ea6dc08af8b6dc5c5a47277f03f662094d4b2 already fixed some of them but this commit fixes a bigger one. Indeed, the menu edition feature was totally broken since the changes. Also, the DOM was messy which broke form navigation, etc. This commit also simplifies the LESS which was uselessly big.
When on a page event for example, when the user choose "Edit menu", a modal is first opened to ask which menu to edit (the top menu or the event menu ?). This feature was broken with a web_editor refactoring. Indeed, the dialog was converted to use the standard dialog class but the widget was still inserted in the DOM thanks to "appendTo" instead of the modal built-in "open" method, preventing it to be properly opened.
Commit 5f98040430ab0ce750382cc0faf57146f8759752 in saas-12 changed some "saved" event to "save" event but forgot to adapt new features which depend on this in 10.0 after forward port.
Since the library nestedSortable was updated to the release 2.1a, at the below revision: https://github.com/odoo/odoo/commit/aa19d9edd02756d87056a44340e36568b3183e21 It was no longer possible, in the front-end, to move the menus: Re-sequence them, put one below another, ... Indeed, in that piece of code, `.item_id` was never set with the new release, while it was the case with the former one. We replace with `.id`, which looks like to have the same behavior.