Implement pubsub samples

[alevenberg]

There are 10 pubsub samples that are missing for C++

https://cloud.google.com/pubsub/docs/samples

This issue will track the implementation

[alevenberg]

Splitting into 3 PRs

1. add pubsub_list_schema_revisions, pubsub_commit_avro_schema, and pubsub_commit_proto_schema
   a. pubsub_list_schema_revisions
   ListSchemaRevisionss
   bazel run //google/cloud/pubsub/samples:samples list-schema-revisions alevenb-test avro-schema

b. pubsub_commit_avro_schema

To test
CreateAvroSchema
bazel run //google/cloud/pubsub/samples:samples create-avro-schema alevenb-test avro-schema ./google/cloud/pubsub/samples/testdata/schema.avsc

ListSchemaRevisionss
bazel run //google/cloud/pubsub/samples:samples list-schema-revisions alevenb-test avro-schema

CommitAvroSchema
bazel run //google/cloud/pubsub/samples:samples commit-avro-schema alevenb-test avro-schema ./google/cloud/pubsub/samples/testdata/revised_schema.avsc

c. pubsub_commit_proto_schema
pubsub_list_schema_revisions
CreateProtobufSchema
bazel run //google/cloud/pubsub/samples:samples create-protobuf-schema alevenb-test protobuf-schema ./google/cloud/pubsub/samples/testdata/schema.proto

ListSchemaRevisionss
bazel run //google/cloud/pubsub/samples:samples list-schema-revisions alevenb-test protobuf-schema

CommitProtobufSchema
bazel run //google/cloud/pubsub/samples:samples commit-protobuf-schema alevenb-test protobuf-schema ./google/cloud/pubsub/samples/testdata/revised_schema.proto

Ran before sending PR

ci/cloudbuild/build.sh -t checkers-pr --docker env GOOGLE_CLOUD_PROJECT=cloud-cpp-testing-resources bazel run //google/cloud/pubsub/samples:samples -- auto
2.
pubsub_get_schema_revision
bazel run //google/cloud/pubsub/samples:samples get-schema-revision alevenb-test protobuf-schema 19d55c5e

pubsub_rollback_schema
bazel run //google/cloud/pubsub/samples:samples rollback-schema alevenb-test protobuf-schema 19d55c5e

pubsub_delete_schema_revision
bazel run //google/cloud/pubsub/samples:samples delete-schema-revision alevenb-test protobuf-schema 19d55c5e

pubsub_create_topic_with_schema_revisions
https://cloud.google.com/pubsub/docs/samples/pubsub-create-topic-with-schema-revisions#pubsub_create_topic_with_schema_revisions-python

Testing for the proto

Executing tests from //google/cloud/pubsub/samples:samples
-----------------------------------------------------------------------------
Schema revision: name: "projects/alevenb-test/schemas/protobuf-schema@6de61b3c"
type: PROTOCOL_BUFFER
revision_id: "6de61b3c"
revision_create_time {
  seconds: 1686593498
  nanos: 750000000
}

Schema revision: name: "projects/alevenb-test/schemas/protobuf-schema@cf99cf26"
type: PROTOCOL_BUFFER
revision_id: "cf99cf26"
revision_create_time {
  seconds: 1686593490
  nanos: 496000000
}

bazel run //google/cloud/pubsub/samples:samples create-topic-with-schema-revisions alevenb-test topic-id protobuf-schema BINARY cf99cf26 6de61b3c

bazel run //google/cloud/pubsub/samples:samples create-topic-with-schema-revisions alevenb-test avro-topic-id avro-schema JSON 18e69ad0 48e5a961

pubsub_update_topic_schema
bazel run //google/cloud/pubsub/samples:samples update-topic-schema alevenb-test avro-topic-id 18e69ad0 48e5a961

[alevenberg]

3 more PRS
4.

pubsub_subscribe_avro_records_with_revisions
https://avro.apache.org/docs/current/api/cpp/html/index.html
https://cloud.google.com/pubsub/docs/samples/pubsub-subscribe-avro-records-with-revisions
-> we aren't currently taking the external dependency

pubsub_create_unwrapped_push_subscription

pubsub_create_cloud_storage_subscription
-> currently only available in staging

Work is in branch: issue-11720-cloud-storage-sample