Fix: Enforce 255-byte filename limit (#8290)

### What problem does this PR solve?

- Add filename length validation (<=255 bytes) for document
upload/rename in both HTTP and SDK APIs
- Update error messages for consistency
- Fix comparison operator in SDK from '>=' to '>' for filename length
check

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

test/testcases/test_sdk_api/test_file_management_within_dataset/test_update_document.py

@@ -25,7 +25,7 @@ class TestDocumentsUpdated:
         "name, expected_message",
         [
             ("new_name.txt", ""),
-            (f"{'a' * (DOCUMENT_NAME_LIMIT - 3)}.txt", "The name should be less than 128 bytes"),
+            (f"{'a' * (DOCUMENT_NAME_LIMIT - 4)}.txt", ""),
             (0, "AttributeError"),
             (None, "AttributeError"),
             ("", "The extension of file can't be changed"),

test/testcases/test_sdk_api/test_file_management_within_dataset/test_upload_documents.py

@@ -113,16 +113,17 @@ class TestDocumentsUpload:
         assert str(excinfo.value) == "No file selected!", str(excinfo.value)
 
     @pytest.mark.p2
-    def test_filename_exceeds_max_length(self, add_dataset_func, tmp_path):
+    def test_filename_max_length(self, add_dataset_func, tmp_path):
         dataset = add_dataset_func
-        fp = create_txt_file(tmp_path / f"{'a' * (DOCUMENT_NAME_LIMIT - 3)}.txt")
+        fp = create_txt_file(tmp_path / f"{'a' * (DOCUMENT_NAME_LIMIT - 4)}.txt")
 
         with fp.open("rb") as f:
             blob = f.read()
 
-        with pytest.raises(Exception) as excinfo:
-            dataset.upload_documents([{"display_name": fp.name, "blob": blob}])
-        assert str(excinfo.value) == "File name should be less than 128 bytes.", str(excinfo.value)
+        documents = dataset.upload_documents([{"display_name": fp.name, "blob": blob}])
+        for document in documents:
+            assert document.dataset_id == dataset.id, str(document)
+            assert document.name == fp.name, str(document)
 
     @pytest.mark.p2
     def test_duplicate_files(self, add_dataset_func, tmp_path):