missing cookie apiKey authentication mechanism

Created by: matteomazza91

Description

Security Scheme Object defines that apiKey can be in "query", "header" or "cookie".
Actually the generator allows only "query" and "header" as shown by the following snippet:

if (SecurityScheme.Type.APIKEY.equals(securityScheme.getType())) {
            cs.isBasic = cs.isOAuth = false;
            cs.isApiKey = true;
            cs.keyParamName = securityScheme.getName();
            cs.isKeyInHeader = securityScheme.getIn() == SecurityScheme.In.HEADER;
            cs.isKeyInQuery = !cs.isKeyInHeader;
} 

Suggest a fix/enhancement

I had already proposed a PR to the swagger-codegen project to solve this issue.
I can start working on it right now.