### 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)

_draw_fbg_boxes(ci, rid, fbg_line_off, it_from, it_to, chr_range.x, chr_range.y, 0);
		
		Color selection_bg = theme_cache.selection_color;
		int sel_start = -1;
		int sel_end = -1;
		if (selection.active && (selection.from_frame->lines[selection.from_line].char_offset + selection.from_char) <= (l.char_offset + TS->shaped_text_get_range(rid).y) && (selection.to_frame->lines[selection.to_line].char_offset + selection.to_char) >= (l.char_offset + TS->shaped_text_get_range(rid).x)) {
			sel_start = MAX(TS->shaped_text_get_range(rid).x, (selection.from_frame->lines[selection.from_line].char_offset + selection.from_char) - l.char_offset);
			sel_end = MIN(TS->shaped_text_get_range(rid).y, (selection.to_frame->lines[selection.to_line].char_offset + selection.to_char) - l.char_offset);
			Vector<Vector2> sel = TS->shaped_text_get_selection(rid, sel_start, sel_end);
			for (int i = 0; i < sel.size(); i++) {
				Rect2 rect = Rect2(sel[i].x + p_ofs.x + off.x, p_ofs.y + off.y - TS->shaped_text_get_ascent(rid), sel[i].y - sel[i].x, TS->shaped_text_get_size(rid).y);
				RenderingServer::get_singleton()->canvas_item_add_rect(ci, rect, selection_bg);
			}
		}
		Vector2 ul_start;
		bool ul_started = false;
		Color ul_color;
		Vector2 dot_ul_start;
		bool dot_ul_started = false;
		Color dot_ul_color;
		Vector2 st_start;
		bool st_started = false;
		Color st_color;
		for (int i = 0; i < gl_size; i++) {
			bool selected = selection.active && (sel_start != -1) && (glyphs[i].start >= sel_start) && (glyphs[i].end <= sel_end);
			Item *it = _get_item_at_pos(it_from, it_to, glyphs[i].start);
			Color font_color = _find_color(it, p_base_color);
			if (_find_underline(it) || (_find_meta(it, nullptr) && underline_meta)) {
				if (!ul_started) {
					ul_started = true;