Figure out how to automate shared services API GW

[galenatjpl]

Figure out how to automate the update of the shared services API GW, upon deployment of a new project/venue.
A new APIGW resource needs to be created, so that API calls will properly get routed to the venue API GW.
The SS APIGW, should reference the URL of the venue APIGW.
Potentially, we can leverage a similar mechanism that the SS HTTPD update process uses, which is to update a configuration file in a SS S3 bucket.

Make sure to think about security issues here.

IDEAS:
-- store/update venue SSM params that specify the proj/venue API Gateway resource config
-- cross-account lambda invoke?