Move some constants to common (#11004)

### What problem does this PR solve?

As title.

### Type of change

- [x] Refactoring

---------

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

rag/app/laws.py

@@ -20,7 +20,7 @@ import re
 from io import BytesIO
 from docx import Document
 
-from api.db import ParserType
+from common.constants import ParserType
 from deepdoc.parser.utils import get_text
 from rag.nlp import bullets_category, remove_contents_table, \
     make_colon_as_title, tokenize_chunks, docx_question_level, tree_merge