### 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)

ul_start = p_ofs + Vector2(off.x, off.y);
					ul_color = font_color;
					ul_color.a *= 0.5;
				}
			} else if (ul_started) {
				ul_started = false;
				float y_off = TS->shaped_text_get_underline_position(rid);
				float underline_width = MAX(1.0, TS->shaped_text_get_underline_thickness(rid) * theme_cache.base_scale);
				draw_line(ul_start + Vector2(0, y_off), p_ofs + Vector2(off.x, off.y + y_off), ul_color, underline_width);
			}
			if (_find_hint(it, nullptr) && underline_hint) {
				if (!dot_ul_started) {
					dot_ul_started = true;
					dot_ul_start = p_ofs + Vector2(off.x, off.y);
					dot_ul_color = font_color;
					dot_ul_color.a *= 0.5;
				}
			} else if (dot_ul_started) {
				dot_ul_started = false;
				float y_off = TS->shaped_text_get_underline_position(rid);
				float underline_width = MAX(1.0, TS->shaped_text_get_underline_thickness(rid) * theme_cache.base_scale);
				draw_dashed_line(dot_ul_start + Vector2(0, y_off), p_ofs + Vector2(off.x, off.y + y_off), dot_ul_color, underline_width, MAX(2.0, underline_width * 2));
			}
			if (_find_strikethrough(it)) {
				if (!st_started) {
					st_started = true;
					st_start = p_ofs + Vector2(off.x, off.y);
					st_color = font_color;
					st_color.a *= 0.5;
				}