Emulation: Fix boot path resolving

* Fix /dev_flash executables path arg. (/host_root is wrong for it)
* Fix usage of /host_root for homebrew applications when it is not mounted, use /app_home.
* Fix path source detection. (don't get fooled by path slashes repetitions, symlinks, '.', ".." and ('\' on Windows))
* Unescape tail of /dev_hdd0 paths.

Utilities/File.h

@@ -648,9 +648,6 @@ namespace fs
 		std::string m_dest{}; // Destination file path
 	};
 
-	// Get real path for comparisons (TODO: investigate std::filesystem::path::compare implementation)
-	std::string escape_path(std::string_view path);
-
 	// Delete directory and all its contents recursively
 	bool remove_all(const std::string& path, bool remove_root = true);