Test: Added test cases for Parse Documents HTTP API (#6235)

### What problem does this PR solve?

cover [parse
documents](https://ragflow.io/docs/dev/http_api_reference#parse-documents)
endpoints

### Type of change

- [x] add test cases

sdk/python/test/libs/utils/__init__.py

@@ -15,7 +15,9 @@
 #
 
 import base64
+import functools
 import hashlib
+import time
 from pathlib import Path
 
 
@@ -35,3 +37,22 @@ def compare_by_hash(file1, file2, algorithm="sha256"):
         return hash_func.hexdigest()
 
     return _calc_hash(file1) == _calc_hash(file2)
+
+
+def wait_for(timeout=10, interval=1, error_msg="Timeout"):
+    def decorator(func):
+        @functools.wraps(func)
+        def wrapper(*args, **kwargs):
+            start_time = time.time()
+            while True:
+                result = func(*args, **kwargs)
+                if result is True:
+                    return result
+                elapsed = time.time() - start_time
+                if elapsed > timeout:
+                    assert False, error_msg
+                time.sleep(interval)
+
+        return wrapper
+
+    return decorator