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/kernel/Device/NullDevice.cpp

@@ -6,7 +6,7 @@ namespace Kernel
 
 	BAN::ErrorOr<BAN::RefPtr<NullDevice>> NullDevice::create(mode_t mode, uid_t uid, gid_t gid)
 	{
-		auto* result = new NullDevice(mode, uid, gid, DevFileSystem::get().get_next_rdev());
+		auto* result = new NullDevice(mode, uid, gid, DevFileSystem::get().get_next_dev());
 		if (result == nullptr)
 			return BAN::Error::from_errno(ENOMEM);
 		return BAN::RefPtr<NullDevice>::adopt(result);