feature: Support VPC Lattice integration as frontend service #639

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This is a feature request to support VPC Lattice integration similar to API GW and ALB.

Serverless Java Container version: eg. 1.5
For both v1 (Spring Boot 2) and v2 (Spring Boot 3.x). Ideally, v2 should be good if v1 is not prioritized.

Implementations: Jersey / Spring / Spring Boot / Spring Boot 2 / Spark
SpringBoot

Framework version: eg SpringBoot 2.2.6.RELEASE
Spring Boot 3.x (if feasible, Spring Boot 2)

Frontend service: REST API / HTTP API / ALB
VPC Lattice

Deployment method: eg SAM, Serverless Framework, Console
N/A

Scenario

Describe what you are trying to accomplish
Support VPC Lattice as the frontend service. The incoming payload for VPC Lattice is different than API GW. This addition will be a new RequestSource, therefore needing a variety of changes related to AwsProxyRequest, AwsProxyResponse, request POJO, response POJO, request reader, response writer, security context, and more

Expected behavior

Describe how you would expect the application to behave
A Spring Boot application running on a Lambda function should work with VPC Lattice as a request source.

Actual behavior

Describe what you are seeing instead
Currently, VPC Lattice is not supported.