Add support for folder deletion (#3635)

### What problem does this PR solve?

Add support for folder deletion.

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

Co-authored-by: liuhua <10215101452@stu.ecun.edu.cn>

api/apps/kb_app.py

                     message="Database error (Document removal)!")
             f2d = File2DocumentService.get_by_document_id(doc.id)
             FileService.filter_delete([File.source_type == FileSource.KNOWLEDGEBASE, File.id == f2d[0].file_id])
+            FileService.filter_delete([File.source_type == FileSource.KNOWLEDGEBASE, File.type == "folder", File.name == kbs[0].name])
             File2DocumentService.delete_by_document_id(doc.id)
 
         if not KnowledgebaseService.delete_by_id(req["kb_id"]):

api/apps/sdk/dataset.py

                     File.id == f2d[0].file_id,
                 ]
             )
+            FileService.filter_delete(
+                [File.source_type == FileSource.KNOWLEDGEBASE, File.type == "folder", File.name == kbs[0].name])
             File2DocumentService.delete_by_document_id(doc.id)
         if not KnowledgebaseService.delete_by_id(id):
             return get_error_data_result(message="Delete dataset error.(Database error)")