Kernel: Rework whole Terminal structure

Serial monitors can now be used as a output. This requires editing
init code for the stdio opening. Serial input is not supported, so qemu
still needs graphical window for ps/2 keyboard.

kernel/include/kernel/FS/DevFS/FileSystem.h

@@ -16,7 +16,7 @@ namespace Kernel
 	
 		void add_device(BAN::StringView path, BAN::RefPtr<Device>);
 
-		dev_t get_next_rdev();
+		dev_t get_next_dev();
 
 	private:
 		DevFileSystem(size_t size)