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_http_api/test_file_management_within_dataset/test_update_document.py

@@ -47,9 +47,9 @@ class TestDocumentsUpdated:
         [
             ("new_name.txt", 0, ""),
             (
-                f"{'a' * (DOCUMENT_NAME_LIMIT - 3)}.txt",
-                101,
-                "The name should be less than 128 bytes.",
+                f"{'a' * (DOCUMENT_NAME_LIMIT - 4)}.txt",
+                0,
+                "",
             ),
             (
                 0,

test/testcases/test_http_api/test_file_management_within_dataset/test_upload_documents.py

@@ -13,7 +13,6 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 #
-
 import string
 from concurrent.futures import ThreadPoolExecutor, as_completed
 
@@ -128,13 +127,12 @@ class TestDocumentsUpload:
         assert res.json()["message"] == "No file selected!"
 
     @pytest.mark.p2
-    def test_filename_exceeds_max_length(self, HttpApiAuth, add_dataset_func, tmp_path):
+    def test_filename_max_length(self, HttpApiAuth, add_dataset_func, tmp_path):
         dataset_id = add_dataset_func
-        # filename_length = 129
-        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")
         res = upload_documents(HttpApiAuth, dataset_id, [fp])
-        assert res["code"] == 101
-        assert res["message"] == "File name should be less than 128 bytes."
+        assert res["code"] == 0
+        assert res["data"][0]["name"] == fp.name
 
     @pytest.mark.p2
     def test_invalid_dataset_id(self, HttpApiAuth, tmp_path):