Support all HTTP error codes

[efgpinto]

We currently only support subset of HTTP errors. I belive this came from the fact that only some had a direct translation to GRPC error codes.

However, I think we need to extend and support all status codes.

I recently tried to implement an API spec which required a return code of 422. The only workaround ATM is to do a .reply using the internal kalix header in metadata.