Refactors the keys_held rolling buffer (#53773)

* rolling key rip

* category

* comment

* oops

code/modules/client/client_defines.dm

@@ -192,3 +192,13 @@
 	/// rate limiting for the crew manifest
 	var/crew_manifest_delay
 
+	/// A buffer of currently held keys.
+	var/list/keys_held = list()
+	/*
+	** These next two vars are to apply movement for keypresses and releases made while move delayed.
+	** Because discarding that input makes the game less responsive.
+	*/
+ 	/// On next move, add this dir to the move that would otherwise be done
+	var/next_move_dir_add
+ 	/// On next move, subtract this dir from the move that would otherwise be done
+	var/next_move_dir_sub

code/modules/client/verbs/reset_held_keys.dm

@@ -0,0 +1,11 @@
+/**
+  * Manually clears any held keys, in case due to lag or other undefined behavior a key gets stuck.
+  *
+  * Hardcoded to the ESC key.
+  */
+/client/verb/reset_held_keys()
+	set name = "Reset Held Keys"
+	set hidden = TRUE
+
+	for(var/key in keys_held)
+		keyUp(key)