constructor(_options, _languageService, _openerService) {
        this._options = _options;
        this._languageService = _languageService;
        this._openerService = _openerService;
        this._onDidRenderAsync = new Emitter();
        this.onDidRenderAsync = this._onDidRenderAsync.event;
    }
Markdown renderer that can render codeblocks with the editor mechanics. This
renderer should always be preferred.