Major project restructuring

Remove unecessary files and made the tree much more cleaner.

Signed-off-by: Ronald Caesar <github43132@proton.me>

core/common/StringUtil.h

@@ -0,0 +1,23 @@
+// Copyright 2025 Xenon Emulator Project. All rights reserved.
+
+#pragma once
+
+#include <algorithm>
+#include <cctype>
+#include <string>
+#include <string_view>
+
+#ifdef _WIN32
+#include <Windows.h>
+#else
+#include <filesystem>
+#endif
+
+namespace Base
+{
+
+[[nodiscard]] std::string UTF16ToUTF8(const std::wstring_view& input);
+[[nodiscard]] std::wstring UTF8ToUTF16W(const std::string_view& str);
+[[nodiscard]] std::string ToLower(const std::string& str);
+
+}  // namespace Base