Block movement now locks turning, migrate old save files to Ctrl (#53871)

The block movement key now correctly locks turning like it used to.

Old save files are now migrated to Ctrl if they didn't bind it to anything before. This correctly replicates the old behavior.

code/modules/client/preferences_savefile.dm

@@ -5,7 +5,7 @@
 //	You do not need to raise this if you are adding new values that have sane defaults.
 //	Only raise this value when changing the meaning/format/name/layout of an existing value
 //	where you would want the updater procs below to run
-#define SAVEFILE_VERSION_MAX	37
+#define SAVEFILE_VERSION_MAX	38
 
 /*
 SAVEFILE UPDATING/VERSIONING - 'Simplified', or rather, more coder-friendly ~Carn
@@ -73,6 +73,20 @@ SAVEFILE UPDATING/VERSIONING - 'Simplified', or rather, more coder-friendly ~Car
 		if(clientfps == 0)
 			clientfps = -1
 
+	if (current_version < 38)
+		var/found_block_movement = FALSE
+
+		for (var/list/key in key_bindings)
+			for (var/bind in key)
+				if (bind == "block_movement")
+					found_block_movement = TRUE
+					break
+			if (found_block_movement)
+				break
+
+		if (!found_block_movement)
+			LAZYADD(key_bindings["Ctrl"], "block_movement")
+
 /datum/preferences/proc/update_character(current_version, savefile/S)
 	return