Add cookie auth support in JWT federation provider

Knox has authentication federation providers to check either a cookie (SSOCookieFederationFilter) or an HTTP header (JWTFederationFilter) for a JWT. However, it cannot do both in the same filter currently.

We need to enhance the JWTFederationFilter to check first for a valid JWT in the hadoop-jwt cookie (cookie name should be configurable) or keep doing what it does today, use the Authorization HTTP header.