### Godot version

Godot 4.0.3

### System information

Windows 10 64 bits NVIDIA GeForce GTX 1060

### Issue description

Ctrl+K is a shortcut normally used to comment out the current line. It works in the shader editor, but for some reason, it doesn't if your shader has the `.gdshaderinc` extension (aka it's a shader include). Shader Includes are the same language, we should be able to use that feature.

### Steps to reproduce

Create a `.gdshaderinc` file. Write some code in it. Observe you can't use Ctrl+K to comment out lines.

### Minimal reproduction project

[CommentLinesShaderInc.zip](https://github.com/godotengine/godot/files/11739881/CommentLinesShaderInc.zip)

err_text = "error(" + itos(err_line) + ") in include " + include_positions[include_positions.size() - 1].file + ":" + itos(include_positions[include_positions.size() - 1].line) + ": " + sl.get_error_text();
				set_error_count(include_positions.size() - 1);
			} else {
				err_line = sl.get_error_line();
				err_text = "error(" + itos(err_line) + "): " + sl.get_error_text();
				set_error_count(0);
			}
			set_error(err_text);
			set_error_pos(err_line - 1, 0);
			get_text_editor()->set_line_background_color(err_line - 1, marked_line_color);
		} else {
			set_error("");
		}
		if (warnings.size() > 0 || last_compile_result != OK) {
			warnings_panel->clear();
		}
		warnings.clear();
		for (List<ShaderWarning>::Element *E = sl.get_warnings_ptr(); E; E = E->next()) {
			warnings.push_back(E->get());
		}
		if (warnings.size() > 0 && last_compile_result == OK) {
			warnings.sort_custom<WarningsComparator>();
			_update_warning_panel();
		} else {
			set_warning_count(0);
		}
	}
	emit_signal(SNAME("script_validated"), last_compile_result == OK); 
}
void ShaderTextEditor::_update_warning_panel() {