### Godot version

Godot 4.0.3

### System information

Windows 10 64 bits NVIDIA GeForce GTX 1060

### Issue description

Ctrl+K is a shortcut normally used to comment out the current line. It works in the shader editor, but for some reason, it doesn't if your shader has the `.gdshaderinc` extension (aka it's a shader include). Shader Includes are the same language, we should be able to use that feature.

### Steps to reproduce

Create a `.gdshaderinc` file. Write some code in it. Observe you can't use Ctrl+K to comment out lines.

### Minimal reproduction project

[CommentLinesShaderInc.zip](https://github.com/godotengine/godot/files/11739881/CommentLinesShaderInc.zip)

bar->hide();
	shader_editor->set_find_replace_bar(bar);
	warnings_panel = memnew(RichTextLabel);
	warnings_panel->set_custom_minimum_size(Size2(0, 100 * EDSCALE));
	warnings_panel->set_h_size_flags(SIZE_EXPAND_FILL);
	warnings_panel->set_meta_underline(true);
	warnings_panel->set_selection_enabled(true);
	warnings_panel->set_context_menu_enabled(true);
	warnings_panel->set_focus_mode(FOCUS_CLICK);
	warnings_panel->hide();
	warnings_panel->connect("meta_clicked", callable_mp(this, &TextShaderEditor::_warning_clicked));
	editor_box->add_child(warnings_panel);
	shader_editor->set_warnings_panel(warnings_panel);
	goto_line_dialog = memnew(GotoLineDialog);
	add_child(goto_line_dialog);
	disk_changed = memnew(ConfirmationDialog);
	VBoxContainer *vbc = memnew(VBoxContainer);
	disk_changed->add_child(vbc);
	Label *dl = memnew(Label);
	dl->set_text(TTR("This shader has been modified on disk.\nWhat action should be taken?"));
	vbc->add_child(dl);
	disk_changed->connect("confirmed", callable_mp(this, &TextShaderEditor::_reload));
	disk_changed->set_ok_button_text(TTR("Reload"));
	disk_changed->add_button(TTR("Resave"), !DisplayServer::get_singleton()->get_swap_cancel_ok(), "resave");
	disk_changed->connect("custom_action", callable_mp(this, &TextShaderEditor::save_external_data));
	trim_trailing_whitespace_on_save = EDITOR_GET("text_editor/behavior/files/trim_trailing_whitespace_on_save");
	add_child(disk_changed);
	_editor_settings_changed();
}