[x] Build out stub Lambdas for the following REST endpoints:
[x] GET /
[x] GET dmps/
[x] POST dmps/
[x] GET dmps/[:dmp_id] (determine if we can do content negotiation in the gateway ... which would mean we can have separate lambdas for each OR if we need to handle the negotiation in a single Lambda)
[x] PUT dmps/[:dmp_id]
[x] PUT dmps/[:dmp_id]/funding (define expected JSON input)
[x] PUT dmps/[:dmp_id]/related_identifier (define expected JSON input)
[x] Build REST API Gateway and connect the endpoints to their corresponding Lambda functions
Create the API Gateway and define the endpoints