feat: Add ExternalRuntimeOptions to BigQuery routine

This change introduces the `ExternalRuntimeOptions` class to the
`google.cloud.bigquery.routine` module, allowing users to configure
runtime options for external routines.

Key changes:
- Created the `ExternalRuntimeOptions` class with setters and getters for
  `container_memory`, `container_cpu`, `runtime_connection`,
  `max_batching_rows`, and `runtime_version`.
- Updated the `Routine` class to include an `external_runtime_options`
  property that accepts an `ExternalRuntimeOptions` object.
- Added comprehensive unit tests for the new class and its integration
  with the `Routine` class, including tests for both valid and invalid
  input values.
- Added additional tests to improve code coverage based on feedback.

Author: google-labs-jules[bot]

tests/unit/routine/test_external_runtime_options.py

@@ -81,6 +81,32 @@ def test_runtime_version(object_under_test):
     assert object_under_test.runtime_version == runtime_version
 
 
+def test_ctor_w_properties(target_class):
+    properties = {
+        "containerMemory": "1G",
+        "containerCpu": 1,
+    }
+    instance = target_class(_properties=properties)
+    assert instance._properties == properties
+
+
+def test_ne(target_class):
+    instance1 = target_class(container_memory="1G")
+    instance2 = target_class(container_memory="2G")
+    assert instance1 != instance2
+
+
+def test_ne_false(target_class):
+    instance1 = target_class(container_memory="1G")
+    instance2 = target_class(container_memory="1G")
+    assert not (instance1 != instance2)
+
+
+def test_eq_not_implemented(object_under_test):
+    assert not (object_under_test == object())
+    assert object_under_test != object()
+
+
 def test_from_api_repr(target_class):
     resource = {
         "containerMemory": "1G",

tests/unit/routine/test_routine.py

@@ -607,6 +607,12 @@ def test_set_remote_function_options_w_none(object_under_test):
     assert object_under_test._properties["remoteFunctionOptions"] is None
 
 
+def test_set_external_runtime_options_w_none(object_under_test):
+    object_under_test.external_runtime_options = None
+    assert object_under_test.external_runtime_options is None
+    assert object_under_test._properties["externalRuntimeOptions"] is None
+
+
 def test_set_data_governance_type_w_none(object_under_test):
     object_under_test.data_governance_type = None
     assert object_under_test.data_governance_type is None