clients: add cbc proxy clients

We are going to invoke a lambda to send a message to the CBC

We need a CBC Proxy Client to do this

The Client will be able to send/update/cancel broadcasts in the CBC

Unless we have configured the app with AWS credentials for the
CBCProxyClient, we just want to use a client that does nothing: the noop
client

The AWS access keys are separate for the CBC Proxy vs other Notify AWS
things because the CBC Proxy lives in another AWS account

Signed-off-by: Toby Lorne <toby.lornewelch-richards@digital.cabinet-office.gov.uk>
Co-authored-by: Pea <pea.tyczynska@digital.cabinet-office.gov.uk>
Co-authored-by: Katie <katie.smith@digital.cabinet-office.gov.uk>

app/__init__.py

@@ -23,6 +23,7 @@ from werkzeug.local import LocalProxy
 
 from app.celery.celery import NotifyCelery
 from app.clients import Clients
+from app.clients.cbc_proxy import CBCProxyClient, CBCProxyNoopClient
 from app.clients.document_download import DocumentDownloadClient
 from app.clients.email.aws_ses import AwsSesClient
 from app.clients.email.aws_ses_stub import AwsSesStubClient
@@ -60,6 +61,7 @@ zendesk_client = ZendeskClient()
 statsd_client = StatsdClient()
 redis_store = RedisClient()
 performance_platform_client = PerformancePlatformClient()
+cbc_proxy_client = CBCProxyNoopClient()
 document_download_client = DocumentDownloadClient()
 metrics = GDSMetrics()
 
@@ -112,6 +114,10 @@ def create_app(application):
     performance_platform_client.init_app(application)
     document_download_client.init_app(application)
 
+    if application.config['CBC_PROXY_AWS_ACCESS_KEY_ID']:
+        cbc_proxy_client = CBCProxyClient()
+    cbc_proxy_client.init_app(application)
+
     register_blueprint(application)
     register_v2_blueprints(application)