Export StandaloneLambdaResponseBody type and constructors

[tysonzero]

Closes #108

[dnikolovv]

Hey, I'm not sure whether this should be done. Does the newer way of setting up lambdas not work for your usecase? It's simpler now, you don't need to construct the StandaloneLambdaResponse.

I'll come up with a more detailed response next week, perhaps even improve the docs.

[NickSeagull]

I thought it was needed for returning the appropriate type, so I pointed him to it, my bad! Looking forward for your response @dnikolovv

[dnikolovv]

Is this helpful?

https://theam.github.io/aws-lambda-haskell-runtime/02-adding-a-handler.html

This + the next section is how you define and then register a handler.

[tysonzero]

In that case is LambdaResult just deprecated entirely? Given that only two of its three constructors can actually be created.

I'm not totally against refactoring the code later, but right now I'm upgrading a lot of packages at once so just trying to put in the least effort possible for each one.

[dnikolovv]

Yes, it's now deprecated. I guess you can try pinning to the version that works for you?