### 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)

fc.instantiate();
			int fnt_size = -1;
			for (int i = 1; i < subtag.size(); i++) {
				Vector<String> subtag_a = subtag[i].split("=", true, 1);
				_normalize_subtags(subtag_a);
				if (subtag_a.size() == 2) {
					if (subtag_a[0] == "name" || subtag_a[0] == "n") {
						String fnt = subtag_a[1];
						Ref<Font> font_data = ResourceLoader::load(fnt, "Font");
						if (font_data.is_valid()) {
							font = font_data;
							def_font = CUSTOM_FONT;
						}
					} else if (subtag_a[0] == "size" || subtag_a[0] == "s") {
						fnt_size = subtag_a[1].to_int();
					} else if (subtag_a[0] == "glyph_spacing" || subtag_a[0] == "gl") {
						int spacing = subtag_a[1].to_int();
						fc->set_spacing(TextServer::SPACING_GLYPH, spacing);
					} else if (subtag_a[0] == "space_spacing" || subtag_a[0] == "sp") {
						int spacing = subtag_a[1].to_int();
						fc->set_spacing(TextServer::SPACING_SPACE, spacing);
					} else if (subtag_a[0] == "top_spacing" || subtag_a[0] == "top") {
						int spacing = subtag_a[1].to_int();
						fc->set_spacing(TextServer::SPACING_TOP, spacing);
					} else if (subtag_a[0] == "bottom_spacing" || subtag_a[0] == "bt") {
						int spacing = subtag_a[1].to_int();
						fc->set_spacing(TextServer::SPACING_BOTTOM, spacing);
					} else if (subtag_a[0] == "embolden" || subtag_a[0] == "emb") {
						float emb = subtag_a[1].to_float();
						fc->set_variation_embolden(emb);