Lambda proxy integration

[sercasti]

1. I updated the Lambda implementation to use an “Integration Proxy” style interface by adding as a dependency the “aws-lambda-java-events” sdk and using the “APIGatewayV2HTTPEvent” artifact in the lambda interfaces
2. Now the lambda receives the full request event and returns the full response event, which includes the content-type definition, the CORS headers, and the response status code.
3. The lambda now uses Amazon powertools-serialization library to bind the incoming body on the request to the internal DTO object for the add and remove endpoints.
4. The lambda parses the incoming Path Parameter “uuid” for the “getUnicornsBasket” from the request event. (event.getPathParameters().get("uuid"))
5. Moved the Lambda to the next version 0.0.2 as these changes are not backwards compatible

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