prevents harming dead when MODE_NO_ATTACK_DEAD (#7734)

# About the pull request

MODE_NO_ATTACK_DEAD makes you think you can not harm dead, but it only
prevented shooting them, did not prevent harm from flames and
explosions. this solves the issue

# Explain why it's good for the game

there is good reason why xenos can not harm dead humans, same goes for
your enemeis in HvH, putting 600 burn on dead is NOT intended. makes the
gamemode more fair and in that way fun.


# Testing Photographs and Procedure
<details>
<summary>Screenshots & Videos</summary>

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screenshots and the `<details>` tags.

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# Changelog
:cl:
fix: MODE_NO_ATTACK_DEAD now prevents harm from explosions and flames
correctly
/:cl:

---------

Co-authored-by: vincibrv <[email protected]>
Co-authored-by: harryob <[email protected]>

code/modules/organs/limbs.dm

@@ -276,6 +276,8 @@
 							no_limb_loss, damage_source = create_cause_data("amputation"),\
 							mob/attack_source = null,\
 							brute_reduced_by = -1, burn_reduced_by = -1)
+	if((brute > 0 || burn > 0) && owner && MODE_HAS_MODIFIER(/datum/gamemode_modifier/disable_attacking_corpses) && owner.stat == DEAD) //if they take positive damage (not healing) we prevent it
+		return 0
 	if((brute <= 0) && (burn <= 0))
 		return 0