server: move server-context to its own cpp|h (#17595)

* git mv

* add server-context.h

* add server-context.h

* clean up headers

* cont : cleanup

* also expose server_response_reader (to be used by CLI)

* fix windows build

* decouple server_routes and server_http

---------

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>

tools/server/CMakeLists.txt

@@ -21,6 +21,8 @@ set(TARGET_SRCS
     server-queue.h
     server-common.cpp
     server-common.h
+    server-context.cpp
+    server-context.h
 )
 set(PUBLIC_ASSETS
     index.html.gz