chore: Adds decorators to mark classes or fucntions as working_in_progress or experimental

User will see warning if they instantiate such class or call such functions.

PiperOrigin-RevId: 769413048

tests/unittests/utils/test_feature_decorator.py

@@ -0,0 +1,42 @@
+import warnings
+
+from google.adk.utils.feature_decorator import experimental
+from google.adk.utils.feature_decorator import working_in_progress
+
+
+@working_in_progress("in complete feature, don't use yet")
+class IncompleteFeature:
+
+  def run(self):
+    return "running"
+
+
+@experimental("api may have breaking change in the future.")
+def experimental_fn():
+  return "executing"
+
+
+def test_working_in_progress_class_warns():
+  with warnings.catch_warnings(record=True) as w:
+    warnings.simplefilter("always")
+
+    feature = IncompleteFeature()
+
+    assert feature.run() == "running"
+    assert len(w) == 1
+    assert issubclass(w[0].category, UserWarning)
+    assert "[WIP] IncompleteFeature:" in str(w[0].message)
+    assert "don't use yet" in str(w[0].message)
+
+
+def test_experimental_method_warns():
+  with warnings.catch_warnings(record=True) as w:
+    warnings.simplefilter("always")
+
+    result = experimental_fn()
+
+    assert result == "executing"
+    assert len(w) == 1
+    assert issubclass(w[0].category, UserWarning)
+    assert "[EXPERIMENTAL] experimental_fn:" in str(w[0].message)
+    assert "breaking change in the future" in str(w[0].message)