feat: add Spanner execute sql query result mode

Add using the execute sql query return result as list of dictionaries.
In each dictionary the key is the column name and the value is the value of
the that column in a given row.

PiperOrigin-RevId: 840909555

tests/unittests/tools/spanner/test_spanner_tool_settings.py

@@ -14,6 +14,8 @@
 
 from __future__ import annotations
 
+from google.adk.tools.spanner.settings import Capabilities
+from google.adk.tools.spanner.settings import QueryResultMode
 from google.adk.tools.spanner.settings import SpannerToolSettings
 from google.adk.tools.spanner.settings import SpannerVectorStoreSettings
 from pydantic import ValidationError
@@ -70,3 +72,26 @@ def test_spanner_vector_store_settings_invalid_vector_length():
   assert "Invalid vector length in the Spanner vector store settings." in str(
       excinfo.value
   )
+
+
+@pytest.mark.parametrize(
+    "settings_args, expected_rows, expected_mode",
+    [
+        ({}, 50, QueryResultMode.DEFAULT),
+        (
+            {
+                "capabilities": [Capabilities.DATA_READ],
+                "max_executed_query_result_rows": 100,
+                "query_result_mode": QueryResultMode.DICT_LIST,
+            },
+            100,
+            QueryResultMode.DICT_LIST,
+        ),
+    ],
+)
+def test_spanner_tool_settings(settings_args, expected_rows, expected_mode):
+  """Test SpannerToolSettings with different values."""
+  settings = SpannerToolSettings(**settings_args)
+  assert settings.capabilities == [Capabilities.DATA_READ]
+  assert settings.max_executed_query_result_rows == expected_rows
+  assert settings.query_result_mode == expected_mode