feat: warnings when instance resources are linked

Signed-off-by: Rachel Powers <508861+Ryex@users.noreply.github.com>

launcher/FileSystem.h

@@ -528,4 +528,6 @@ bool canLinkOnFS(FilesystemType type);
  */
 bool canLink(const QString& src, const QString& dst);
 
+uintmax_t hardLinkCount(const QString& path);
+
 }