goserver - Allow to specify headers to add to the response

Created by: randomswdev

This pull request is intended to provide the capability to specify headers to include in the response.

This is needed, for example, to allow a REST API to redirect the client to a new URL (using the Location header).

This pull request includes also the changes in the pull request https://github.com/OpenAPITools/openapi-generator/pull/8144

@antihax @grokify @kemokemo @bkabrda