Hitby refactor (#19624)

Refactored hitby to be in line with TG's version.
Refactored item weight defines to a more clear naming scheme, also in
line with TG's version.
Refactored how the movement bumps are handled, ported signals to handle
them, in preparation for the movement update.
Fixed disposal hit bouncing the hitting atom on the wall.
Items do not push other items anymore if they are tiny.

code/modules/holodeck/HolodeckObjects.dm

@@ -263,7 +263,7 @@
 	throw_speed = 1
 	throw_range = 5
 	throwforce = 0
-	w_class = ITEMSIZE_SMALL
+	w_class = WEIGHT_CLASS_SMALL
 	atom_flags = ATOM_FLAG_NO_BLOOD
 	item_icons = list(
 		slot_l_hand_str = 'icons/mob/items/weapons/lefthand_energy.dmi',
@@ -296,13 +296,13 @@
 	if (active)
 		force = 33
 		icon_state = "sword[item_color]"
-		w_class = ITEMSIZE_LARGE
+		w_class = WEIGHT_CLASS_BULKY
 		playsound(user, 'sound/weapons/saberon.ogg', 50, 1)
 		to_chat(user, SPAN_NOTICE("[src] is now active."))
 	else
 		force = 3
 		icon_state = "sword0"
-		w_class = ITEMSIZE_SMALL
+		w_class = WEIGHT_CLASS_SMALL
 		playsound(user, 'sound/weapons/saberoff.ogg', 50, 1)
 		to_chat(user, SPAN_NOTICE("[src] can now be concealed."))
 
@@ -322,7 +322,7 @@
 	name = "basketball"
 	item_state = "basketball"
 	desc = "Here's your chance, do your dance at the Space Jam."
-	w_class = ITEMSIZE_LARGE //Stops people from hiding it in their bags/pockets
+	w_class = WEIGHT_CLASS_BULKY //Stops people from hiding it in their bags/pockets
 	drop_sound = 'sound/items/drop/basketball.ogg'
 	pickup_sound = 'sound/items/pickup/basketball.ogg'