feat: remove FSearch integration and related files

- Deleted FSearch related source and header files to streamline the project.
- Updated CMake configuration to remove references to FSearch.
- Adjusted searcher implementation to focus on the new file name searcher.

Log: clean up project by removing obsolete FSearch integration

Author: Kakueeen

.reuse/dep5

@@ -63,11 +63,6 @@ Files: tests/cmake/modules/FindGMock.cmake
 Copyright: 2011 Matej Svec
 License: MIT
 
-# fsearch
-Files: 3rdparty/fsearch/*
-Copyright: 2020 Christian Boxdörfer
-License: GPL-2.0-or-later
-
 # interfaces
 Files: 3rdparty/interfaces/*
 Copyright: 2017 The Qt Company Ltd.