* Fix server network restart

[lemantisee]

Fix restarting network module in NetImguiServer.
This is necessary for restarting NetImguiServer without restarting whole application.

[sammyfreg]

So, you stop call Shutdown and then Restart?
The only thing I could see missing, is making sure that the shutdown completed before the we reach line 366,

[lemantisee]

I call NetImguiServer::App::Shutdown and than NetImguiServer::App::Startup.
In NetImguiServer::App::Shutdown gbShutdown is set to true which disables loop in NetworkConnectRequest_Send to establish new connections with clients. So after call NetImguiServer::App::Startup we can't see clients in network.