### 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)

if (p_idx < 4) { 
		_menu_option(bookmarks_menu->get_item_id(p_idx));
	} else {
		shader_editor->goto_line(bookmarks_menu->get_item_metadata(p_idx));
	}
}
void TextShaderEditor::_make_context_menu(bool p_selection, Vector2 p_position) {
	context_menu->clear();
	if (p_selection) {
		context_menu->add_shortcut(ED_GET_SHORTCUT("ui_cut"), EDIT_CUT);
		context_menu->add_shortcut(ED_GET_SHORTCUT("ui_copy"), EDIT_COPY);
	}
	context_menu->add_shortcut(ED_GET_SHORTCUT("ui_paste"), EDIT_PASTE);
	context_menu->add_separator();
	context_menu->add_shortcut(ED_GET_SHORTCUT("ui_text_select_all"), EDIT_SELECT_ALL);
	context_menu->add_shortcut(ED_GET_SHORTCUT("ui_undo"), EDIT_UNDO);
	context_menu->add_shortcut(ED_GET_SHORTCUT("ui_redo"), EDIT_REDO);
	context_menu->add_separator();
	context_menu->add_shortcut(ED_GET_SHORTCUT("script_text_editor/indent"), EDIT_INDENT);
	context_menu->add_shortcut(ED_GET_SHORTCUT("script_text_editor/unindent"), EDIT_UNINDENT);
	context_menu->add_shortcut(ED_GET_SHORTCUT("script_text_editor/toggle_comment"), EDIT_TOGGLE_COMMENT);
	context_menu->add_shortcut(ED_GET_SHORTCUT("script_text_editor/toggle_bookmark"), BOOKMARK_TOGGLE);
	context_menu->set_position(get_screen_position() + p_position);
	context_menu->reset_size();
	context_menu->popup();
}
TextShaderEditor::TextShaderEditor() {