FileSystem: Purge GetDisplayNameFromPath()

Redundant function.

common/FileSystem.cpp

@@ -531,11 +531,6 @@ static std::string_view::size_type GetLastSeperatorPosition(const std::string_vi
 	return last_separator;
 }
 
-std::string FileSystem::GetDisplayNameFromPath(const std::string_view& path)
-{
-	return std::string(Path::GetFileName(path));
-}
-
 std::string_view Path::GetDirectory(const std::string_view& path)
 {
 	const std::string::size_type pos = GetLastSeperatorPosition(path, false);