### Godot version

v4.1.stable.official [970459615]

### System information

Godot v4.1.stable - Windows 10.0.22621 - Vulkan (Forward+) - dedicated NVIDIA GeForce MX330 (NVIDIA; 30.0.15.1169) - 11th Gen Intel(R) Core(TM) i5-1135G7 @ 2.40GHz (8 Threads)

### Issue description

Calling `RichTextLabel`'s `select_all` method has no visual indicator, but it must have one. 

### Steps to reproduce

- Add `RichTextLabel` node
- Set `selection_enabled` value to be `true`
- Call `$RichTextLabel.select_all() `method in `_ready`

### Minimal reproduction project

[RichTextLabel_bug.zip](https://github.com/godotengine/godot/files/12098913/RichTextLabel_bug.zip)

return Rect2(theme_cache.normal_style->get_offset(), get_size() - theme_cache.normal_style->get_minimum_size());
}
RichTextLabel::Item *RichTextLabel::_get_item_at_pos(RichTextLabel::Item *p_item_from, RichTextLabel::Item *p_item_to, int p_position) {
	int offset = 0;
	for (Item *it = p_item_from; it && it != p_item_to; it = _get_next_item(it)) {
		switch (it->type) {
			case ITEM_TEXT: {
				ItemText *t = static_cast<ItemText *>(it);
				offset += t->text.length();
				if (offset > p_position) {
					return it;
				}
			} break;
			case ITEM_NEWLINE: {
				offset += 1;
				if (offset == p_position) {
					return it;
				}
			} break;
			case ITEM_IMAGE: {
				offset += 1;
				if (offset > p_position) {
					return it;
				}
			} break;