Fix http2 stream pointer

Response and Request are now movable, so lets use that to our advantage
and make this no longer require a pointer.  This removes a couple NOLINT
exceptions in our code, and cleans up a lot of places where we could
potentially get a nullptr.

Tested:
enabled http2-experimental option.
Loaded service root from redfish in curl with logging enabled, logging
verified http/2 was being used.

Redfish service validator passes.
Curl compiled with http returns service root correctly.

Change-Id: I65e11a2311be982df594086413d52838235e1a0c
Signed-off-by: Ed Tanous <ed@tanous.net>
diff --git a/http/http_request.hpp b/http/http_request.hpp
index cf0f417..e375f28 100644
--- a/http/http_request.hpp
+++ b/http/http_request.hpp
@@ -51,8 +51,8 @@
     Request(const Request& other) = default;
     Request(Request&& other) = default;
 
-    Request& operator=(const Request&) = delete;
-    Request& operator=(const Request&&) = delete;
+    Request& operator=(const Request&) = default;
+    Request& operator=(Request&&) = default;
     ~Request() = default;
 
     boost::beast::http::verb method() const