Update document template schema to reference object types

- Changed the type of `testObject` from Mixed to ObjectId and added a refPath to `objectType`, enhancing the schema's ability to manage relationships with other documents.
- This update improves data integrity and allows for more structured querying of related objects.

src/database/schemas/management/documenttemplate.schema.js

@@ -45,7 +45,8 @@ const documentTemplateSchema = new Schema(
       default: '<Container></Container>',
     },
     testObject: {
-      type: Schema.Types.Mixed,
+      type: Schema.Types.ObjectId,
+      refPath: 'objectType',
       required: false,
     },
   },