fixes for summer update 2023

[AHauntedArmy]

• Don't destroy on load, in Start, prevents the bepinex manager gameobject from getting destroyed, so all mods work.
• fixed nullref from a new UnityEvent field added to GorillaPressableButton, being invoked on press.
• add the custom gamemodes to the new network prefab pool system.

[ghost]

Thanks