Codechange: [Network] split CloseSocket and CloseConnection more clearly (#9261)

* Codechange: [Network] split CloseSocket and CloseConnection more clearly

- CloseSocket now closes the actual OS socket.
- CloseConnection frees up the resources to just before CloseSocket.
- dtors call CloseSocket / CloseConnection where needed.

src/network/core/tcp_content.cpp

@@ -137,17 +137,6 @@ const char *ContentInfo::GetTextfile(TextfileType type) const
 	return ::GetTextfile(type, GetContentInfoSubDir(this->type), tmp);
 }
 
-/**
- * Close the actual socket.
- */
-void NetworkContentSocketHandler::CloseSocket()
-{
-	if (this->sock == INVALID_SOCKET) return;
-
-	closesocket(this->sock);
-	this->sock = INVALID_SOCKET;
-}
-
 /**
  * Handle the given packet, i.e. pass it to the right
  * parser receive command.