🍃 Allow spiders to walk on walls and ceilings (minus our bases)

[TheBORM]

Hi Devs, Consider allowing spiders to walk up vertical surfaces and ceilings on map structures, and inside tunnels.

After all, that's how it works IRL, and it would help make Grounded 2 further stand out from its predecessor.

Just block this from occuring on base materials, so we can feel safe there