Converts move intents to /decl/move_intent (#8993)

* Converts move intents to /decl/move_intent

Adds /decl/move_intent/walk and /decl/move_intent/run.

Switches all move intent checks to use the new IS_RUNNING and IS_WALKING macros.

Renames and refactors /mob/living/proc/set_m_intent() to /mob/living/proc/set_move_intent(decl/move_intent/intent).

Removes the unnecessary /mob/var/m_int and associated code.

Updates all move intent setters to use set_move_intent().

* Swaps incorrect config values

Swaps incorrect move delays since I got them backwards somehow, oopsies.

* Adds suggested ?. operator

Compactifies two if statements using the ?. operator instead.

code/modules/organs/internal/intestine.dm

@@ -16,8 +16,8 @@
 	if (. >= 2)
 		if(prob(1))
 			owner.custom_pain("Your abdomen feels like it's tearing itself apart!",1)
-			owner.m_intent = "walk"
-			owner.hud_used.move_intent.icon_state = "walking"
+			if(!IS_WALKING(owner))
+				owner.set_move_intent(/decl/move_intent/walk)
 
 /obj/item/organ/internal/intestine/xeno
 	color = "#555555"

code/modules/organs/internal/kidneys.dm

@@ -38,8 +38,8 @@
 	if (. >= 2)
 		if(prob(1))
 			owner.custom_pain("You feel extremely tired, like you can't move!",1)
-			owner.m_intent = "walk"
-			owner.hud_used.move_intent.icon_state = "walking"
+			if(!IS_WALKING(owner))
+				owner.set_move_intent(/decl/move_intent/walk)
 
 /obj/item/organ/internal/kidneys/grey
 	icon_state = "kidneys_grey"