### Godot version

v4.0.beta.custom_build [13f0158]

### System information

Windows 10

### Issue description

When doing operations (`begin_complex_operation` and `end_complex_operation`) with multiple selections in TextEdit, some of these selections don't revert upon undo. This behavior is affects some of script editor's operations, like duplicate selection and delete lines.

### Steps to reproduce

Open script editor, make multiple selections. Keep in mind what you have selected. Do duplicate selection (ctrl+shift+D). Undo (ctrl+Z). Compare the result to what you remember.

### Minimal reproduction project

N/A
Ref<InputEventKey> k = p_event;
	if (k.is_valid()) {
		if (!k->is_pressed()) {
			return;
		}
		
		if (has_focus() && editable && (k->get_unicode() >= 32)) {
			handle_unicode_input(k->get_unicode());
			accept_event();
		}
	}
}
bool TextEdit::alt_input(const Ref<InputEvent> &p_gui_input) {
	Ref<InputEventKey> k = p_gui_input;
	if (k.is_valid()) {
		if (!k->is_pressed()) {
			if (alt_start && k->get_keycode() == Key::ALT) {
				alt_start = false;
				if ((alt_code > 0x31 && alt_code < 0xd800) || (alt_code > 0xdfff && alt_code <= 0x10ffff)) {
					handle_unicode_input(alt_code);
				}
				return true;