[WIP] Fix 3D shadowcasting.

[kevingranade]

Summary

SUMMARY: Bugfixes "Correct behavior of 3D shadowcasting mode"

Purpose of change

3D shadowcasting has a number of rendering bugs remaining, fix them.
A non-exhaustive list:
As in #29175 shockers are sometimes able to see and target you through a floor. With some debugging I determined the cause to be 3D shadowcasting.
When standing cardinally adjacent to a single opaque tile (wall or adult tree, etc), in 2D shadowcasting the area behind the tree is obscured, but in 3D it is visible.
When standing adjacent to a wall corner, in 2D shadowcasting the first tile of the wall is visible and the rest is occluded, in 3D the entire wall and anything behind it is visible.
3D shadowcasting does not cast directly up or down, so there's a shadow directly above and below the player.

Describe the solution

This is going to be a progressive process since I don't know what the problem is.

• Extend shadowcasting test to trigger 3D shadowcasting and test 3D scenarios.
• Add tests that characterize the breakage.
• Replace recursive shadowcasting with iterative shadowcasting as outlined in Further shadowcasting optimizations #23373. In addition to being more performant, this should be easier to analyze and test.
• Fix the bugs.

[kevingranade]

You can see the 5 scenarios that are failing, if anyone has noticed any other artifacts caused by toggling 2d/3d vision mode (there are probably many), please let me know and I'll look into them.

After further testing, it looks like the failure mode that let shockers shoot through ceilings is unrelated, it has something to do with map shifting logic.