feat: Introduce write protected mode to BigQuery tools

This allows to protect against any write operations (e.g. update or delete a table), useful for some agents that must only be used in a read-only mode, while the user may have write permissions.

PiperOrigin-RevId: 769803741

tests/unittests/tools/bigquery/test_bigquery_tool_config.py

@@ -0,0 +1,27 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import annotations
+
+from google.adk.tools.bigquery.config import BigQueryToolConfig
+import pytest
+
+
+def test_bigquery_tool_config_experimental_warning():
+  """Test BigQueryToolConfig experimental warning."""
+  with pytest.warns(
+      UserWarning,
+      match="Config defaults may have breaking change in the future.",
+  ):
+    BigQueryToolConfig()