This PR adds animated tilesets! I spent the day working on these, and it wasn't easy. This is primarily to help animate the All-Stars' grass tiles. You should be able to animate the other tilesets as well, but I haven't tested them.
JSONs are provided in the assets for Conveyer Belts and Liquids. There's two ways to animate the tilesets. The first is by the traditional way as used by `AnimatedSprite2D`, and the other is by how Godot animates tilesets normally as seen with the conveyer belts and liquids.
The last thing is that while doing this, I actually managed to fix the Resource Pack bug where reloading also reloads the blocks! It was surprisingly straightforward. I just edited the `BlockClass.gd` file to erase the cells when a block is hit or destroyed.
Let me know if you have any suggestions for things I should change or fix.
