Comment unreferenced local labels

[Narishma-gb]

This PR attempts to remove unused local labels, replacing them with comments. A few comments are added:

• .checkIfUsingMultiturnMove and .MultiturnMoveCheck, to provide context for a useless instruction
• TransformEffect_ where code optimization led to a stack of bugs
• PokeText and UnusedPlayerNameLengthFunc with JPN context
• ZeroMemory with short use description

PrintNicknameAndUnderscores gets new labels and more *_NAME_LENGTH constants usage.

Added AnimationUnusedShakeScreen label to include the lone instruction there.

Added an ASSERT in Colosseum_Script, since it's using the script from TradeCenter.

There's a new ASSERT in PlayerStepOutFromDoor, because BIT_EXITING_DOOR does not belong to wStatusFlags5.

I'm not sure about the hypothesis made here. As BIT_EXITING_DOOR is later either set or reset based on IsPlayerStandingOnDoorTile result, perhaps the first instruction is indeed meant to reset BIT_UNKNOWN_5_1, although it has no visible effect on gameplay.