This is related to #28898. With the addition of the http nio transport,
we now have two different modules that provide http transports.
Currently most of the http logic lives at the module level. However,
some of this logic can live in server. In particular, some of the
setting of headers, cors, and pipelining. This commit begins this moving
in that direction by introducing lower level abstraction (HttpChannel,
HttpRequest, and HttpResonse) that is implemented by the modules. The
higher level rest request and rest channel work can live entirely in
server.
fcf1e41e42