deprecate existsDir; use dirExists instead (#14884)

tests/manyloc/keineschweine/keineschweine.nim

@@ -446,7 +446,7 @@ ingameClient.registerHandler(KeyF12, down, proc() = toggleSpec())
 ingameClient.registerHandler(KeyF11, down, toggleShipSelect)
 ingameClient.registerHandler(MouseLeft, down, handleLClick)
 when defined(recordMode):
-  if not existsDir("data/snapshots"):
+  if not dirExists("data/snapshots"):
     createDir("data/snapshots")
   ingameClient.registerHandler(keynum9, down, proc() =
     if not isRecording: startRecording()

tests/manyloc/keineschweine/lib/client_helpers.nim

@@ -103,7 +103,7 @@ proc saveCurrentFile() =
   let
     path = expandPath(currentFileTransfer.assetType, currentFileTransfer.fileName)
     parent = parentDir(path)
-  if not existsDir(parent):
+  if not dirExists(parent):
     createDir(parent)
     echo("Created dir")
   writeFile path, currentFIleTransfer.data

tests/manyloc/nake/nakefile.nim

@@ -77,7 +77,7 @@ task "testskel", "create skeleton test dir for testing":
 task "clean", "cleanup generated files":
   var dirs = @["nimcache", "server"/"nimcache"]
   dirs.apply(proc(x: var string) =
-    if existsDir(x): removeDir(x))
+    if dirExists(x): removeDir(x))
 
 task "download", "download game assets":
   var