Move some constants to common (#11004)

### What problem does this PR solve?

As title.

### Type of change

- [x] Refactoring

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

graphrag/light/smoke.py

@@ -21,7 +21,7 @@ import networkx as nx
 import logging
 import trio
 
-from api.db import LLMType
+from common.constants import LLMType
 from api.db.services.document_service import DocumentService
 from api.db.services.knowledgebase_service import KnowledgebaseService
 from api.db.services.llm_service import LLMBundle