Fix null NextLevel

[Letaryat]

• Probably fixed null nextlevel so it wont randomly change map to null even on custom gamemode (and I think without gamemode_servers.txt as well),
• Added a RegisterEventHandler for EventCsWinPanelMatch so when match is ended and voting is still going it will automatically end voting and select a next map,
• Added a really small feature that will execute server command: mp_pause_match for EndOfMapVote when enabled in config, When EndOfMapVote is ended it executes mp_unpause_match.

Plugin was tested only with bots so I am not sure if everything is perfect but when tested seemed okay.

[Letaryat]

As onemore said on discord thread:

nextlevel works with classic maps and maps you added to a Workshop collection assigned to the server. Workshop collection has a limit of about 100 maps. So if you want to add more workshop maps to your server, the nextlevel will not work with workshop maps which are not in the collection

"My fix" works with maps that are on the server either as a default CS2 maps or when they were downloaded from workshop collection.
Because of that, probably it would be easier to use method ChangeNextMap from changeMapManager at the EventCsWinPanelMatch in EndOfMapVote.cs but not sure if I can do that and create PR.

[Oz-Lin]

Thanks, I will have a look after work