Fix desync when cancelling a gravship launch

[cmlee119]

Fixes #965.

Problem

PatchGravshipPreLaunchCancel.Postfix closed the GravshipTravelSession with:

GravshipTravelUtils.CloseSessionAt(Find.CurrentMap.Tile);

Cancelling a gravship launch is a synced command, so this runs on every peer — but Find.CurrentMap is the map each peer's camera is on, i.e. local UI state, not synchronized simulation state. A peer whose camera is on another map calls CloseSessionAt with the wrong tile and never closes the session, so that map stays paused only for them. Because GravshipTravelSession.IsCurrentlyPausing(map) => map == Map gates whether the map ticks, the per-map tick counts then diverge and the game desyncs (Map instances don't match / Wrong random state on map N).

Of the four CloseSessionAt call sites in GravshipTravelSessionPatches.cs, this was the only one using Find.CurrentMap; the others already pass deterministic tiles (curTile / landingTile / takeoffTile).

Fix

Close the session by looking it up instead of by the local camera. There is exactly one open GravshipTravelSession while a launch is pending, so a small CloseAllSessions() helper closes it deterministically on every peer.

Testing

• Reproduced on vanilla Multiplayer + Odyssey (async time + multifaction, no third-party mods): host launches from the gravship map with a client looking at another map, host cancels → client desyncs, gravship map paused only on the client.
• With the fix, cancelling releases the pause on the gravship map on all peers and no desync occurs.
• Source/Client builds clean (Release).

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Investigated and written with the help of Claude (Anthropic).