Add root redirect to /docs/v2

[mbklein]

Description

Primary purpose

This PR reconfigures how APIs are mounted within the dcapi... API Gateway Domain:

/ - root API
└── api
    ├── v1 - v1 API
    └── v2 - v2 API

The root API has two routes:

• /docs/v2 - the v2 documentation
• / - a tiny function that does nothing but redirect to /docs/v2

Deployment changes

In addition, the following changes simplify the lambda packages created by SAM and prevent redundant deployments:

• Make src its own NPM project
• Move runtime dependencies from /package.json to src/package.json
• Create preinstall script in root that installs src packages
• Add CodeUri: ./src to all API functions

As a result:

• Only changes to template.yaml or src/**/* will trigger an update of all the API lambdas on deploy
• The new root redirect lambda can be deployed on its own without the entire API package coming along for the ride

Documentation changes

• Add query and as to the GET /search OpenAPI spec
• Add IiifPresentationManifest as a possible search response type

Testing

This change has already been deployed to staging, so you can test:

Docs

• https://dcapi.rdc-staging.library.northwestern.edu/
• https://dcapi.rdc-staging.library.northwestern.edu/docs/v2/
• Navigate through to the Swagger UI docs and try the interactive bits

DC API v2

• Try a bunch of API requests using https://dcapi.rdc-staging.library.northwestern.edu/api/v2/ as the base
  • e.g., https://dcapi.rdc-staging.library.northwestern.edu/api/v2/search?query=berkeley&as=iiif

DC API v1

• Try a bunch of elastic-proxy requests using https://dcapi.rdc-staging.library.northwestern.edu/api/v1/ as the base
  • e.g., https://dcapi.rdc-staging.library.northwestern.edu/api/v1/search/meadow/_doc/4e40344a-5d12-43de-9bb7-75c216b0e603