Fix map_export admin verb not saving objects properly (#90998)

## About The Pull Request

When using the `map_export` admin verb the following things are fixed:
- All objects density, anchored, opacity, atom_integrity, and
resistance_flags vars are saved
- Multi-tile objects being spammed on all tiles the sprite reaches
- Dirt decals error icon
- Airlocks error icon and to save welded state
- Dark Wizard Simple Mobs error icon
- Closets to save welded, open, and locked states
- Air alarms to save name
- Air scrubbers/vents to save name and welded states
- APCs to save name, charge, cell, lighting, equipment, and
environmental states
- APCs spawning a duplicated terminal underneath it when one already
exists
- SMES to save charge, input, and output states
- Holodecks to revert any holodeck turfs to the empty turf and skip
saving any hologram items
- Photos and Paintings error icons
- Bloody Footprints error icons
- False Walls error icons
- Docking Ports runtimes because the map template var would change
- Effects (lasers, portals, beams, sparks, etc.) saving when they should
be omitted

I would have loved to get `component_parts` to save for machines and
turf decals, but perhaps that is for another day since it requires
complicated solutions.

Here are some before and after pictures:


![StrongDMM_209k6PXSaQ](https://github.com/user-attachments/assets/27f0a80b-3cbc-4862-a218-612d52fa0e4f)


![StrongDMM_5PdRfLTZ4l](https://github.com/user-attachments/assets/3bbfd724-4b51-47c5-8cff-02687250fc1e)


![StrongDMM_F4DPOGz5K7](https://github.com/user-attachments/assets/1130ded8-3062-469a-ad4a-d437d89a68da)


![StrongDMM_BIa554dsGv](https://github.com/user-attachments/assets/440d6b38-dbbf-47c0-ad9a-5165504d104e)

## Why It's Good For The Game
Better map saving code.

## Changelog
🆑
fix: Fix `map_export` admin verb not properly saving a massive amount of
objects.
/🆑

code/game/objects/effects/decals/cleanable/humans.dm

@@ -293,6 +293,9 @@
 	dryname = "dried footprints"
 	drydesc = "HMM... SOMEONE WAS HERE!"
 
+/obj/effect/decal/cleanable/blood/footprints/get_save_vars()
+	return ..() - NAMEOF(src, icon_state)
+
 /obj/effect/decal/cleanable/blood/footprints/Initialize(mapload, footprint_sprite)
 	src.footprint_sprite = footprint_sprite
 	. = ..()