PixelmonShaderCompat

Fixed the bug where underwater Pokémon were invisible.

1. Render underwater Pokémon only when the player is underwater.
2. Do not render Pokémon above the water surface while the player is underwater.
3. Render shallow-water Pokémon in shallow regions that are two blocks deep and within a circle of radius 5 centered on the player.
4. Due to rendering limitations, Pokémon will not enter the shader pack rendering pipeline. All the above requirements are for proper display of Pokémon; otherwise, Pokémon will stick to your screen like stickers, which looks weird.