Refactor riot damage + add 'pre-burnt' generator

[RenechCDDA]

Summary

None

Purpose of change

#79943

This PR breaks up the bashing, item moving, and fire-setting into separate standardized functions. It aims to eliminate 'magic numbers' and prepare the code to be loaded from JSON definitions.

Additionally, another generator is added along the same principles. 'Pre-brunt'. This is used to simulate fires having already happened before the player visited, and is intended to largely be a 1:1 replacement for fires for later arrivals.

Describe the solution

#79943

For pre-burnt structures we designate a square, or a circle, or some area, and we say "That had a fire". We replace anything with the WALL flag with a hardcoded terrain, burnt wall or whatever. We replace floors with a similar one. Outside areas get torched into dirt. Delete all furniture and items in the affected area, litter some ash piles.

The current implementation simply burns the entire OMT, without trying to make any fun shapes.

Describe alternatives you've considered

Testing

(Taken during development, floors were not properly burned. They are burned now, and look like t_dirtfloor)

Additional context

Ugh git makes a really awful looking diff for this.

[RenechCDDA]

Known issues:

The blood generators will run on some of the OMTs that get pre-burned. This results in burned buildings with bloodstains in them, which looks weird. This might be resolvable with cleanup code to remove all existing fields, but I'm not sure that's a good idea.

Roofs are unaffected by the burning, which can look odd from a z-level up. Not sure what I'm going to do about that, just replacing all roofs with a burnt roof isn't very interesting.

As previously mentioned, but I must point out again: This burns the entire square OMT to the ground, at roughly the same rate as previous fire prevalence. The squareness can look weird. Yes it all can look weird.

The blood generators were not broken up in this PR. They use a ton of magic numbers and untangling them is going to be a pain. (No offense to quill, I'm just less familiar with it as I didn't write the code)

Because the 'magic numbers' were so bad (my fault), the relative prevalence of each effect may need to be tweaked. Again. But this time it should be able to stick, with no further huge changes in logic. The results should be obviously appropriate to the numbers we put in, in ways that make sense.