Network cleanup (#6302)

* Cleanup network headers

* Move peerhandler to a specific header to reduce compilation times
* Move socket.cpp/h to network folder

* More work

* Network code cleanups

* Move socket.{cpp,h} to network folder
* Move Address object to network/address.{cpp,h}
* Move network exceptions to network/networkexceptions.h
* Client: use unique_ptr for Connection
* Server/ClientIface: use shared_ptr for Connection

* Format fixes

* Remove socket.cpp socket.h from clang-format whitelist

* Also fix NetworkPacket code style & make it under clang-format

src/CMakeLists.txt

@@ -442,7 +442,6 @@ set(common_SRCS
 	serverlist.cpp
 	serverobject.cpp
 	settings.cpp
-	socket.cpp
 	sound.cpp
 	staticobject.cpp
 	subgame.cpp