added some code

wrote some code to test some functionallity

src/client_backend/scan.h

@@ -1,3 +1,4 @@
 #pragma once
 #include <string>
-void ListFilesRecursive(const std::string& directory);
+void ListFilesRecursive(const std::string& directory,int thread_id);
+int scan_hash(const std::string& filename, const std::string& searchString);