Add PRR A5 switcher

https://www.nexusmods.com/railroader/mods/913

PRR A5/LegosLibraryOfStuff/Definitions/PRR A5 EXT.json

@@ -0,0 +1,8 @@
+{
+  "identifier": "ls-040-a5",
+  "newIdentifier": "ls-040-a5-ext",
+  "clone": true,
+  "cloneDefault": false,
+  "name": "PRR A5 - 55S66a Extended Bunker",
+  "tenderIdentifier": "55s66a-ext"
+}