Improve CFlashMenuObject::UpdateNetwork

[ccomrade]

Remove CFlashMenuObject::UpdateNetwork function, which calls setNetwork Flash function on frame. Does it actually do something other than showing no connection symbol in multiplayer lobby? @griseraner

Update: Use our own ServerBrowser::LastRequestSucceeded instead of problematic INetwork::HasNetworkConnectivity.

This fixes no connection symbol always shown in multiplayer lobby under Linux 🐧, where INetwork::HasNetworkConnectivity always returns false when there's no recent network channel activity. In this case, it does some questionable checks of network adapters via Windows API. Definitely not something we want in main thread.

INetwork::HasNetworkConnectivity is also called on frame in CHUD::OnPostUpdate, but that one should be fine because it's called only in-game and only when gEnv->bMultiplayer is true. Therefore, network channel activity is there and it returns quickly without calling potentially blocking Windows API functions.

Thanks to Furyaner for pointing out that INetwork::HasNetworkConnectivity is the culprit here. 🙂

[ccomrade]

Now multiplayer lobby shows no connection symbol when server browser request fails. This is more reliable than network adapter checks in INetwork::HasNetworkConnectivity because connected network adapter does not mean that we have internet connection or that master server is available.