POT Generation ignores instantiated nodes in .tscn

[ghost]

Godot version

v4.0.3.stable.official [5222a99]

System information

N/A

Issue description

The POT Generation ignores instantiated scenes.

Investigating the source code, it's probably because of this check:

godot/editor/plugins/packed_scene_translation_parser_plugin.cpp

Lines 55 to 58 in 5222a99

	String node_type = state->get_node_type(i);
	if (!ClassDB::is_parent_class(node_type, "Control") && !ClassDB::is_parent_class(node_type, "Window")) {
	continue;
	}

Because instantiated nodes returns empty for the type here:

godot/scene/resources/packed_scene.cpp

Lines 1417 to 1421 in 5222a99

	StringName SceneState::get_node_type(int p_idx) const {
	ERR_FAIL_INDEX_V(p_idx, nodes.size(), StringName());
	if (nodes[p_idx].type == TYPE_INSTANTIATED) {
	return StringName();
	}

Steps to reproduce

1. Open the MRP;
2. Trigger the POT Generation in the ProjectSettings;
3. Open the generated .pot and note that the instantiated node text wasn't serialized, but the local node was.

Minimal reproduction project

pot_generation_fails_for_instanced_nodes.zip

[Okxa]

Reported previously here: #74194

[AThousandShips]

Duplicate of #74194