Update handling for non-competitive set import

Gen3 item paste -> Gen3 item import => take item ID as is
once parsing moves starts, break if any following lines are not move
lines
Closes #2412 , thanks @The-Fireplace  !

PKHeX.Core/Editing/ShowdownSet.cs

@@ -200,6 +200,9 @@ namespace PKHeX.Core
                     continue;
                 }
 
+                if (movectr != 0)
+                    break;
+
                 var split = line.Split(LineSplit, StringSplitOptions.None);
                 var valid = split.Length == 1
                     ? ParseSingle(line) // Nature

PKHeX.Core/PKM/Util/ItemConverter.cs

@@ -180,6 +180,9 @@ namespace PKHeX.Core
             if (item <= 0)
                 return 0;
 
+            if (destFormat == srcFormat)
+                return item;
+
             if (destFormat != srcFormat && srcFormat <= 3) // past gen items
             {
                 if (destFormat > 3) // try remapping