If a player drops before start, it gets sad

[voces]

A todo was detected in a replay.

• Replay: https://wc3stats.com/games/29595
• Player: verit#11278
• Message: if a player drops before start, it gets sad

This exact behavior isn't a problem with the new team picking, but resiliency should be built for leavers at all stages.

• [x] networkio handles players leave before the proxy version check finishes.
• [x] networkio handles players leaving with an open request
• [x] Team picking works fine if someone leaves before stating a preference.
• [x] Team picking works fine if someone leaves after stating a preference but before everyone else has.
• [x] Team picking works fine if someone leaves after everyone has stated a preference but the fetch isn't complete.
• [x] Game logic handles someone leaving in beat and start phases.