### 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)

_validate_line_caches();
	int line_count = 0;
	int to_line = main->first_invalid_line.load();
	for (int i = 0; i < to_line; i++) {
		MutexLock lock(main->lines[i].text_buf->get_mutex());
		if ((line_count <= p_line) && (p_line <= line_count + main->lines[i].text_buf->get_line_count())) {
			float line_offset = 0.f;
			for (int j = 0; j < p_line - line_count; j++) {
				line_offset += main->lines[i].text_buf->get_line_size(j).y + theme_cache.line_separation;
			}
			return main->lines[i].offset.y + line_offset;
		}
		line_count += main->lines[i].text_buf->get_line_count();
	}
	return 0;
}
float RichTextLabel::get_paragraph_offset(int p_paragraph) {