NetworkPkg:HttpDxe: Code changes to support HTTP PUT/POST operations
    
    Code changes enables HttpDxe to handle PUT/POST operations.
    EfiHttpRequest assumes "Request" and "HttpMsg->Headers" can
    never be NULL. Also, HttpResponseWorker assumes HTTP Reponse
    will contain headers. We could have response which could contain
    only a string (HTTP 100 Continue) and no headers. Code changes
    tries to do-away from these assumptions, which would enable
    HttpDxe to support PUT/POST operations.
    
    Contributed-under: TianoCore Contribution Agreement 1.0
    Signed-off-by: Hegde, Nagaraj P nagaraj-p.hegde@hpe.com
    Reviewed-By: Wu Jiaxin <jiaxin.wu@intel.com>
    Reviewed-by: Fu Siyuan <siyuan.fu@intel.com>