Prevent TurnDirectory.StartFirstRound from firing multiple times

[IceRaptor]

There appears to be a bug with the MissionControl (maybe?) implementation of additional lances. When the dropship lands, it looks like it invokes TurnDirector.OnDropshipAnimationComplete which ultimately ends up calling TurnDirector.StartFirstRound. This can lead to the round 'starting' multiple times.

We need to put a gate in on TurnDirector.StartFirstRound() to do nothing is GameHasBegun = true. Fix should be named something like 'PreventMultipleFirstRoundStarts'?

[IceRaptor]

From #ticket-4729 on RT server:

Weird
It seems like Round 1 started ... 4 times?
2021-04-08T09:59:11 CombatLog.RoundSequence [LOG] [[[============== Round 1 Begin! ================]]]

2021-04-08T09:59:12 CombatLog.RoundSequence [LOG] [[[============== Round 1 Begin! ================]]]

2021-04-08T09:59:12 CombatLog.RoundSequence [LOG] [[[============== Round 1 Begin! ================]]]

2021-04-08T09:59:20 CombatLog.RoundSequence [LOG] [[[============== Round 1 Begin! ================]]]
No, at least 5 times
2021-04-08T09:58:53 EncounterLogic.Dialogue [LOG] PlayNextMessage: message count 0
2021-04-08T09:58:53 CombatLog.RoundSequence [LOG] [[[============== Round 1 Begin! ================]]]
WTF
My guess is that this is ultimately getting called from all the dropships deploying extra units
Since there's a path through TurnDirector.OnDropshipAnimationComplete to TurnDirector.CheckGameBegin which calls StartFirstRound()
Which happens to be in the log after the first turn for the Hitman
2021-04-08T09:59:13 CombatLog.RoundSequence [LOG] Team TargetTeam becoming active
2021-04-08T09:59:13 MissionControl [DEBUG] [AI] [Round '1' Phase '9' Unit Action '1'] ['TargetTeam' unit 'Hitman HM-1r' AI type 'CoreAITree'] Log Node
2021-04-08T09:59:13 MissionControl [DEBUG] [AI] [HasFollowLanceTargetNode] False
...
2021-04-08T09:59:20 CombatLog.RoundSequence [LOG] TurnDirector.OnDropshipAnimationComplete
2021-04-08T09:59:20 CombatLog.RoundSequence [LOG] [[[============== Round 1 Begin! ================]]]
My guess is that this is a MissionControl bug
Since I think that's what spawns the extra lances?