[FIX] web_editor: fix drag and drop a snippet in a modal

When a modal is open, allow the drop of a snippet only in this
modal.

Part of https://github.com/odoo/odoo/pull/61998
task-2312878

X-original-commit: 2f38816f279717bca38166a22c4f692a7f1d10c0

addons/web_editor/static/src/js/editor/snippets.editor.js

@@ -1256,6 +1256,13 @@ var SnippetsMenu = Widget.extend({
     _activateInsertionZones: function ($selectorSiblings, $selectorChildren) {
         var self = this;
 
+        // If a modal is open, the drop zones must be created only in this modal
+        const $openModal = self.getEditableArea().find('.modal:visible');
+        if ($openModal.length) {
+            $selectorSiblings = $openModal.find($selectorSiblings);
+            $selectorChildren = $openModal.find($selectorChildren);
+        }
+
         // Check if the drop zone should be horizontal or vertical
         function setDropZoneDirection($elem, $parent, $sibling) {
             var vertical = false;