Add authentication for haskell-servant

Created by: 7omb

Adds support for API key, basic and bearer authentication in the OpenAPI specification. OAuth and multiple authentication schemes simultaneously are not implemented. The implementation uses servants generalized authentication.

If the OpenAPI specification does not specify an authentication mechanism it is compatible with the existing implementation. I added examples without authentication and for the different schemes here. The command:

./mvnw integration-test -f ./samples/server/petstore/haskell-servant/pom.xml

passes on my machine with BUILD SUCCESS.

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