BattleTest arguments should make the game be considered in PlayTest mode

[Mimigris]

When starting a battle from RPG Maker through the battle test menu (BattleTest ID argument for RPG Maker, or --battle-test for the EasyRPG command), the game is considered as not being in PlayTest mode, while RPG_RT considers the game to be in PlayTest mode. Due to this, if the RPG_RT executable of a game is replaced by the Player, and that a test battle is launched, it will not be possible to open the debug menu, unless the PlayTest argument was also specified.