Initial PR

[hrodmn]

We have a functioning federated collection discovery deployment!

• API: https://discover-api.dit.maap-project.org/
• Client application: https://discover.dit.maap-project.org/

Outline of changes:

• deploy Github Action workflow
  • deploys the CDK stack
  • build the client app and uploads to S3
• CDK Python app with:
  • the Federated Collection Discovery API deployed on a Lambda with an API gateway
  • the Federated Collection Discovery client app deployed in an S3 bucket, served by CloudFront

The two files with most of the action are infrastructure/app.py and .github/workflows/deploy.yaml