Add context to the go-server generated code

[randomswdev]

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Update the go-server code genertor in order to:

1. return 400 in case of an invalid input parameter (very likely is not an internal error).
2. use baseName instead of paramName when gettin a parameter from maps (this makes difference for a parameter like "user-id")
3. pass the ctx to the called handlers, so that they can take decisions based on the calling context and propagate it in ase of down calls.
4. allow handlers to return a status code. And handler that creates a resource should be allowed to return HTTP 201 instead of HTTP 200.
5. allow an handler to return a reponse function in order to fully customize the response. This is useful when, for example, redirecting a requestor; in this case both a custom state and custom headers have to be returned.

@antihax @bvwells @grokify @kemokemo @bkabrda please review.

[wing328]

@randomswdev thanks for the PR. Is it correct to say that this PR introduces breaking changes as the method signature has changed?

[randomswdev]

Yes, this merge request changes the signature of the generated methods. While the changes are breaking ones, I think that adding the context propagation is much needed to allow generating really useful go stubs.

[randomswdev]

Closing as, currently, this has been lready implemented by:
#7214
#7397