Ashwalker Shrine Remap (shiptest-ss13#2931)

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Completely remaps Ashwalker_Shrine into a new map: The Buried Shrine.
An unknown temple buried and ruined by volcanic activity. Who it
belonged to before it was destroyed is unknown, but some of their riches
yet remain buried inside. (Note, this is distinctly **Not** The
Necropolis, and not *explicitly* ashwalker in origin. The walls have
been renamed to represent this.)

SDMM:
![StrongDMM-2024-04-23 22 37
23](https://github.com/shiptest-ss13/Shiptest/assets/95449138/2dcf4e18-7278-423b-9bfa-a13fc3972dcf)
![StrongDMM-2024-04-23 22 37
24](https://github.com/shiptest-ss13/Shiptest/assets/95449138/efdc9fca-c9bd-44dd-b103-c0bf3a3fb712)

Ingame:

![image](https://github.com/shiptest-ss13/Shiptest/assets/95449138/bd997ac3-6de6-40a4-a23a-8fd4cd34296b)
(Fun fact: See those tiles in the lava? They sink when you walk over
them and come back up after a few seconds. Good luck! :])
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Redone lavaland ruins that don't suck are good. This PR has the added
benefit of making the formerly necropolis walls not *strictly*
necropolis related due to its dubious chances at remaining in the lore.
They're good looking walls.
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:cl:
add: remapped and renamed ashwalker_shrine into
lavaland_surface_buried_shrine
add: Necropolis walls have been renamed to thick stone walls.
/:cl:

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