message: Implemented react progress buttons markup
diff: import * as React from "react";
  import { SurveyNavigationBase } from "./reactSurveyNavigationBase";
  import { ReactElementFactory } from "./element-factory";
  +import { PageModel } from "../page";
  export class SurveyProgressButtons extends SurveyNavigationBase {
  constructor(props: any) {
  @@ -8,9 +9,44 @@ export class SurveyProgressButtons extends SurveyNavigationBase {
  }
  render(): JSX.Element {
  return (
  - <div>Progress Buttons Navigations</div>
  + <div className={this.css.progressButtonsContainerCenter}>
  + <div className={this.css.progressButtonsContainer}>
  + <img className={this.getScrollButtonCss(true)}></img>
  + <div className={this.css.progressButtonsListContainer}>
  + <ul className={this.css.progressButtonsList}>
  + {this.getListElements()}
  + </ul>
  + </div>
  + <img className={this.getScrollButtonCss(false)}></img>
  + </div>
  + </div>
  );
  }
  + protected getScrollButtonCss(isLeftScroll: boolean): string {
  + return "";
  + }
  + protected getListElements(): JSX.Element[] {
  + let buttons: JSX.Element[] = [];
  + this.survey.visiblePages.forEach((page: PageModel) => {
  + buttons.push(this.renderListElement(page));
  + });
  + return buttons;
  + }
  + protected renderListElement(page: PageModel): JSX.Element {
  + return (
  + <li key={"listelement" + page.visibleIndex} className={this.getListElementCss(page)}>
  + <div className={this.css.progressButtonsPageTitle}>
  + {page.navigationTitle || page.name}
  + </div>
  + <div className={this.css.progressButtonsPageDescription}>
  + {page.navigationDescription}
  + </div>
  + </li>
  + );
  + }
  + protected getListElementCss(page: PageModel): string {
  + return "";
  + }
  }
  ReactElementFactory.Instance.registerElement("survey-progress-buttons", (props) => {
  