Mob attackedby / check_block refactor, plus some minor cleanup of attack_x procs (#79563)

## About The Pull Request

- Deletes `spec_attacked_by`
- Elements simple/basic mob attack threshold
- There was a skeleton mob that "mimics armor" but didn't use the actual
mimicing armor thing we have, so I changed that.
- Moves `check_shields` down to the living level, renames it to
`check_block`
 - Martial art blocking is now signalized (only CQC uses it anyways) 
- Cleaned up a bit of `attack_x` procs, but not a lot. Should have an
entire PR dedicated to this .... mess.
 - Deprecates `/obj/item/melee`

## Why It's Good For The Game

Second verse, same as the first. 

- Less bad species related procs. 
- Largely brings a lot of code in line, making combat more consistent
across types.
- Makes it a lot easier to add new code relating to blocking or taking
damage.

## Changelog

🆑 Melbert
refactor: Refactored another large chuck of attack code, primarily
involving melee item attacks and non-human mob attacks. Report if you
see anything weird
fix: Pacifists clicking on simple robots or silicons no longer causes
sparks
fix: Blocked thrown batons are now properly... blocked
/🆑

code/modules/mob/living/basic/clown/clown.dm

@@ -370,7 +370,6 @@
 	speed = 1
 	melee_damage_lower = 10
 	melee_damage_upper = 15
-	force_threshold = 10 //lots of fat to cushion blows.
 	damage_coeff = list(BRUTE = 1, BURN = 1, TOX = 1, CLONE = 2, STAMINA = 0, OXY = 1)
 	attack_verb_continuous = "slams"
 	attack_verb_simple = "slam"
@@ -395,7 +394,7 @@
 
 	AddElement(/datum/element/swabable, CELL_LINE_TABLE_GLUTTON, CELL_VIRUS_TABLE_GENERIC_MOB, 1, 5)
 	AddComponent(/datum/component/tameable, food_types = list(/obj/item/food/cheesiehonkers, /obj/item/food/cornchips), tame_chance = 30, bonus_tame_chance = 0, after_tame = CALLBACK(src, PROC_REF(tamed)))
-
+	AddElement(/datum/element/damage_threshold, 10) //lots of fat to cushion blows.
 
 /mob/living/basic/clown/mutant/glutton/attacked_by(obj/item/item, mob/living/user)
 	if(!check_edible(item))