fix(blockEditor): Ensure JSON is parse correctly on field variables (dotCMS#31398)

This pull request includes changes to the `edit_field.jsp` file in the
`dotCMS` project to properly handle and escape JSON values in field
variables. The most important changes are focused on ensuring that JSON
values are correctly processed and escaped to avoid issues with double
quotes.

Key changes:

* Added logic to process each field variable and escape JSON values
properly in `edit_field.jsp`.
* Introduced a mechanism to handle double quotes in JSON values when
setting field variables in `edit_field.jsp`.


https://github.com/user-attachments/assets/ab145b7f-06bc-41e2-8720-122b9eb65369

Author: zJaaal

dotCMS/src/main/webapp/html/portlet/ext/contentlet/field/edit_field.jsp

@@ -242,8 +242,9 @@
                 Logger.error(this.getClass(), e.getMessage());
             }
 
-            List<FieldVariable> acceptTypes=APILocator.getFieldAPI().getFieldVariablesForField(field.getInode(), user, false);
-            String fieldVariablesContent = mapper.writeValueAsString(acceptTypes); // Field Variables
+            List<FieldVariable> acceptTypes = APILocator.getFieldAPI().getFieldVariablesForField(field.getInode(), user, false);
+            String fieldVariablesContent = StringEscapeUtils.escapeJavaScript(mapper.writeValueAsString(acceptTypes));
+
             %>
             <script src="/html/showdown.min.js"></script>
             <div  id="block-editor-<%=field.getVelocityVarName()%>-container">