SDK for session (#2354)

### What problem does this PR solve?

Includes SDK for creating, updating sessions, getting sessions, listing
sessions, and dialogues
#1102 
### Type of change

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

---------

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

sdk/python/ragflow/modules/base.py

@@ -18,8 +18,8 @@ class Base(object):
                     pr[name] = value
         return pr
 
-    def post(self, path, param):
-        res = self.rag.post(path, param)
+    def post(self, path, param, stream=False):
+        res = self.rag.post(path, param, stream=stream)
         return res
 
     def get(self, path, params):