Consistently rename post battle event scripts

[Narishma-gb]

Most event battles do not use DisplayEnemyTrainerTextAndStartBattle and EndTrainerBattle to trigger battle start, or handle post battle events. End battle event scripts share the same initial code, to check battle result:

	ld a, [wIsInBattle]
	cp $ff

Currently, labels fall into 5 categories: "AfterBattle", "Beat", "Defeated", "EndBattle", and "PostBattle".

CeruleanCityRivalDefeatedScript
CeruleanCityRocketDefeatedScript
ChampionsRoomRivalDefeatedScript
MtMoonB2FDefeatedSuperNerdScript
PokemonTower2FDefeatedRivalScript

CeruleanGymMistyPostBattleScript
CinnabarGymBlainePostBattleScript
FightingDojoKarateMasterPostBattleScript
FuchsiaGymKogaPostBattleScript
PewterGymBrockPostBattle
Route12SnorlaxPostBattleScript
Route16SnorlaxPostBattleScript
SaffronGymSabrinaPostBattle
ViridianGymGiovanniPostBattle

RocketHideoutB4FBeatGiovanniScript

Route22Rival1AfterBattleScript
Route22Rival2AfterBattleScript
Route24AfterRocketBattleScript
SilphCo11FGiovanniAfterBattleScript
SilphCo7FRivalAfterBattleScript
SSAnne2FRivalAfterBattleScript
VermilionGymLTSurgeAfterBattleScript

OaksLabRivalEndBattleScript
AgathasRoomAgathaEndBattleScript
BrunosRoomBrunoEndBattleScript
LancesRoomLanceEndBattleScript
LoreleisRoomLoreleiEndBattleScript

CinnabarGymOpenGateScript
PokemonTower6FMarowakBattleScript

Just like trainer texts share the same pattern (Battle, EndBattle, AfterBattle), it would be interesting to name these in a same fashion across all map scripts. "Defeated" and "Beat" should not be used, as these scripts are run regardless of battle result. I would personally go for "PostBattleScript", to set them apart from AfterBattleText, that are displayed only when a battle is won.

There are a few special cases:
OaksLabRivalEndBattleScript does not check battle result.
Elite 4 EndBattle scripts make a combined use of generic trainer scripts (to set trainer flags) and custom scripts, to force display of after battle text.
CinnabarGymOpenGateScript is actually a post battle script, with a self-explanatory label.

Edit: added PokemonTower6FMarowakBattleScript, which is also a post-battle event script.