### 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)

warnings_panel->push_cell();
		warnings_panel->add_text(w.get_message());
		warnings_panel->pop(); 
	}
	warnings_panel->pop(); 
	set_warning_count(warning_count);
}
void ShaderTextEditor::_bind_methods() {
	ADD_SIGNAL(MethodInfo("script_validated", PropertyInfo(Variant::BOOL, "valid")));
}
ShaderTextEditor::ShaderTextEditor() {
	syntax_highlighter.instantiate();
	get_text_editor()->set_syntax_highlighter(syntax_highlighter);
}
void TextShaderEditor::_menu_option(int p_option) {
	switch (p_option) {
		case EDIT_UNDO: {
			shader_editor->get_text_editor()->undo();
		} break;
		case EDIT_REDO: {
			shader_editor->get_text_editor()->redo();
		} break;
		case EDIT_CUT: {
			shader_editor->get_text_editor()->cut();
		} break;
		case EDIT_COPY: {
			shader_editor->get_text_editor()->copy();
		} break;
		case EDIT_PASTE: {