Tile enhance: occlusion, collision, y sort

[lorentzo]

• Figure out how to use collision for tiles -- https://docs.godotengine.org/en/stable/tutorials/2d/using_tilesets.html#adding-collision-navigation-and-occlusion-to-the-tileset
• Figure out how to use occlusion for tiles -- https://docs.godotengine.org/en/stable/tutorials/2d/using_tilesets.html#adding-collision-navigation-and-occlusion-to-the-tileset
• Figure out y sorting

• Must be enabled both in tile map properties and in tile map node itself (see attached img)