feat: update to the latest version of the code generator (#147)

The compute protos are now [available in googleapis/googleapis](https://github.com/googleapis/googleapis/tree/master/google/cloud/compute/v1), and the generated code is also available in googleapis/googleapis-gen [here](https://github.com/googleapis/googleapis-gen/tree/master/google/cloud/compute/v1/compute-small-v1-py). This PR pulls in the latest version of the generated client from googleapis-gen, which may have significant differences. I've added the `do not merge` label while we discuss whether any differences could break user code.

This PR also deletes `synth.py` and adds configuration files for owl bot. owl bot will save time for maintainers as it will automatically open PRs when there are updates in googleapis-gen without requiring maintainers to run synthtool to build the client from protos. Additionally, similar to autosynth, PRs will be automatically opened when there are updates to templated files.

fix(deps): require google-api-core >=2.2.0
fix(deps): require proto-plus >=1.19.7
docs: list oneofs in docstring
fix: add 'dict' annotation type to 'request'
feat: support self-signed JWT flow for service accounts
chore(samples): Merging usage bucket tests into one, to avoid race conditions

Author: parthea

compute/compute/snippets/sample_default_values.py

@@ -112,10 +112,10 @@ def disable_usage_export(project_id: str) -> None:
     """
     projects_client = compute_v1.ProjectsClient()
 
-    # Updating the setting with None will disable the
-    # usage report generation.
+    # Setting `usage_export_location_resource` to an
+    # empty object will disable the usage report generation.
     operation = projects_client.set_usage_export_bucket(
-        project=project_id, usage_export_location_resource=None)
+        project=project_id, usage_export_location_resource={})
 
     op_client = compute_v1.GlobalOperationsClient()
 

compute/compute/snippets/test_sample_default_values.py

@@ -51,9 +51,8 @@ def test_set_usage_export_bucket_default(capsys: typing.Any,
     assert(uel.bucket_name == '')
     assert(uel.report_name_prefix == '')
 
-
-def test_set_usage_export_bucket_custom(capsys: typing.Any,
-                                        temp_bucket: storage.Bucket) -> None:
+    # Testing setting a custom export bucket. Keeping this in one test function
+    # to avoid race conditions, as this is a global setting for the project.
     set_usage_export_bucket(project_id=PROJECT, bucket_name=temp_bucket.name,
                             report_name_prefix=TEST_PREFIX)
     time.sleep(5)  # To make sure the settings are properly updated