feat: Add httpEvent.operationId to the request context

[qswinson]

Description

AWS ApiGateway defines a operationId value for each http event. This value is available in the running Lambda in the event.requestContext.operationName property. This property value is very helpful if validating requests against an OpenApi spec.

This PR takes the operationId value and makes it available in the event model for both LambdaProxyIntegrationEvent and LambdaProxyIntegrationEventV2

Motivation and Context

This supplies a value that is available when running the Serverless deployment in the AWS environment, but until now, not available in the offline environment.

How Has This Been Tested?

I have added unit and integration tests. We have also been using this code internally for the past year.

Screenshots (if appropriate):

[pgrzesik]

Hey @qswinson - this looks great - thanks a lot for submitting a PR. I've rerun the tests because it seems like they failed due to an unrelated flaky connection. Once all is good, I'll merge the PR