force_switch is forced before the events of a battle are processed

[caymansimpson]

When we get a force_switch request, Showdown sends the request object and then the events of the turn that led up to that request afterwards. This isn't handled in poke-env, where we're forced to make a decision based on no information about what transpired earlier in the turn.

Here's a printout of the path of poke-env during execution:

in player._handle_battle_message [['>battle-gen9vgc2024regg-93'], ['', 'request', '{"forceSwitch":[false,true],"side":{"name":"elitefurretai","id":"p1","pokemon":[redacted for brevity],"noCancel":true,"rqid":6}']]
in player.handle_battle_request
in choose_move on turn #1; force_switch: [False, True].
in player._handle_battle_message [['>battle-gen9vgc2024regg-93'], ['', ''], ['', 't:', '1728869837'], ['', '-terastallize', 'p1b: Raichu', 'Ground'], ['', 'move', 'p1a: Delibird', 'Fake Out', 'p2a: Delibird'], ['', '-damage', 'p2a: Delibird', '83/100'], ['', 'move', 'p1b: Raichu', 'Volt Switch', 'p2b: Raichu'], ['', '-resisted', 'p2b: Raichu'], ['', '-damage', 'p2b: Raichu', '82/100']]```