multiplayer: Support client reconnect mid-game

[ManManson]

Describe the feature you'd like Sometimes there are connectivity issues (be it temporary network flickering or firewall configuration-related things) between the host and clients in MP games, which result in clients being dropped from the game. Currently there is no way for clients to reconnect to an active game session, so there's no way to continue playing other than re-hosting the game.

WZ host should support clients reconnection in this case by providing an option to pause the game and wait for some time (configurable, also should be cancelable by the host) for those clients which didn't leave the game in a graceful manner (by sending a proper "leaving" message) to re-connect.

Describe why do you think it is needed This enhancement would greatly improve user experience for those who run the game within an unstable network environment (e.g. low-bandwidth connections, congested Wi-Fi networks).

The feature-request has been raised on the official Discord server in this thread.