`Control::gui_input` is not exposed

### Godot version

4.2.1

### godot-cpp version

4.2

### System information

Windows 11

### Issue description

`Control::gui_input` is not exposed and `Control::_gui_input` is not its GDExtension counterpart, not allowing sending events to other `Control` nodes with specific behaviours.

The use case is trying to reproduce the behaviour of Godot visual shader editor add node dialogue, where you can filter the options with a `LineEdit` on focus, while also being able to go up and down with the keyboard among the filtered member options in the `Tree`.


This is the code you want to be able to call to sent events to `Tree *member` (from https://github.com/godotengine/godot/blob/master/editor/plugins/visual_shader_editor_plugin.cpp)...

```cpp
void VisualShaderEditor::_sbox_input(const Ref &p_ie) {
Ref ie = p_ie;
if (ie.is_valid() && (ie->get_keycode() == Key::UP || ie->get_keycode() == Key::DOWN || ie->get_keycode() == Key::ENTER || ie->get_keycode() == Key::KP_ENTER)) {
members->gui_input(ie);
node_filter->accept_event();
}
}
```
...but changing `members->gui_input(ie);` to `members->_gui_input(ie);` has not the same results, as `_gui_input()` in GDExtension has only overriding purposes as of now.

I'll quote a comment by @Zylann from https://github.com/Zylann/godot_voxel/blob/master/editor/graph/voxel_graph_node_dialog.cpp as it seems he found the same issue:

> // TODO GDX: `Control::gui_input()` is not exposed to GDExtension, can't forward events.
// This is what `VisualShaderEditor::_sbox_input` does.
// `_gui_input` is exposed, but that's only for user implementation, not for calling directly...
// Also `gui_input` is a name already taken in GDScript, so if it gets exposed some day, it will need a
// different name.
//
// _tree->gui_input(key_event);

Will it be exposed correctly in the future?

### Steps to reproduce

As explained in the description, try to use `_gui_input()` on any `Control` child class.

### Minimal reproduction project

No minimal reproduction project needed.