fix: Add async context manager return types (#355)

* fix: Add async context manager return types

chore: Mock return_value should not populate oneof message fields

chore: Support snippet generation for services that only support REST transport

chore: Update gapic-generator-python to v1.11.0
PiperOrigin-RevId: 545430278

Source-Link: googleapis/googleapis@601b532

Source-Link: googleapis/googleapis-gen@b3f18d0
Copy-Tag: eyJwIjoiLmdpdGh1Yi8uT3dsQm90LnlhbWwiLCJoIjoiYjNmMThkMGY2NTYwYTg1NTAyMmZkMDU4ODY1ZTc2MjA0NzlkN2FmOSJ9

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

packages/google-analytics-admin/google/analytics/admin_v1alpha/services/analytics_admin_service/async_client.py

@@ -13258,7 +13258,7 @@ async def sample_delete_event_create_rule():
             metadata=metadata,
         )
 
-    async def __aenter__(self):
+    async def __aenter__(self) -> "AnalyticsAdminServiceAsyncClient":
         return self
 
     async def __aexit__(self, exc_type, exc, tb):

packages/google-analytics-admin/google/analytics/admin_v1beta/services/analytics_admin_service/async_client.py

@@ -5390,7 +5390,7 @@ async def sample_run_access_report():
         # Done; return the response.
         return response
 
-    async def __aenter__(self):
+    async def __aenter__(self) -> "AnalyticsAdminServiceAsyncClient":
         return self
 
     async def __aexit__(self, exc_type, exc, tb):

packages/google-analytics-admin/samples/generated_samples/snippet_metadata_google.analytics.admin.v1alpha.json

@@ -8,7 +8,7 @@
     ],
     "language": "PYTHON",
     "name": "google-analytics-admin",
-    "version": "0.18.0"
+    "version": "0.1.0"
   },
   "snippets": [
     {

packages/google-analytics-admin/samples/generated_samples/snippet_metadata_google.analytics.admin.v1beta.json

@@ -8,7 +8,7 @@
     ],
     "language": "PYTHON",
     "name": "google-analytics-admin",
-    "version": "0.18.0"
+    "version": "0.1.0"
   },
   "snippets": [
     {