Currently in network::Service, post() takes a void() function handler and DeadlineTimer takes a void(std::error_code ec) function handler - update both of these so they use void(realm::Status) for the function handler to match the changes in SyncSocketProvider.

This will require changes to the Server and the DefaultSocketFactory classes as well.

In the case of post() the value provided to the function handler will likely always be Status::OK(), but may need to be updated if there is a way to cancel any pending event loop tasks.