Separating the stack

[mbudm]

Separate the stack currently defined in one serverless.yml file into db, s3, api and cognito.

This allows for more control over what is deployed when but it also introduces complexity with coordinating release of components.

Related to #1

[mbudm]

Stack list could be:

• config endpoint and cognito. It is the cognito IDs that are read from config endpoint. These could deploy to a separate subdomain. Other info the client needs like table name and service endpoint (via custom domain) can be configured from env vars or SSM parameter store
• functions (api gateway). if we do want this endpoint then this stack could add the new cloudfront dist to the SSM parameter store
• dynamodb
• s3 bucket

Versioning...?