Support atomic directory promotion across platforms

internal/fileops/rename_noreplace_windows.go

@@ -0,0 +1,19 @@
+//go:build windows
+
+package fileops
+
+import "golang.org/x/sys/windows"
+
+func checkAtomicDirectoryPromotionSupport() error { return nil }
+
+func renameDirectoryNoReplace(src, dst string) error {
+	from, err := windows.UTF16PtrFromString(src)
+	if err != nil {
+		return err
+	}
+	to, err := windows.UTF16PtrFromString(dst)
+	if err != nil {
+		return err
+	}
+	return windows.MoveFileEx(from, to, 0)
+}