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/network/clientpackethandler.cpp

@@ -31,6 +31,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "server.h"
 #include "util/strfnd.h"
 #include "network/clientopcodes.h"
+#include "network/connection.h"
 #include "script/scripting_client.h"
 #include "util/serialize.h"
 #include "util/srp.h"
@@ -97,7 +98,7 @@ void Client::handleCommand_Hello(NetworkPacket* pkt)
 		m_chosen_auth_mech = AUTH_MECHANISM_NONE;
 		m_access_denied = true;
 		m_access_denied_reason = "Unknown";
-		m_con.Disconnect();
+		m_con->Disconnect();
 	}
 
 }