### Feature and motivation

Adding parameter for subpath configuration so inside container application can work on different path than root.

I've tested rewrite rules on ingress and they do not work correctly.

### Usage example

Currently application works on http://localhost:4444 inside of the container, unfortunately in ingress implementation with reverse-proxy application will not respond correctly to ingress configuration where path is configured different than "/"
New parameter would allow to change base URL of the application to work on http://localhost/selenium:4444 which will allow correct communication with ingress.
private static final String GRID_RESOURCE = "javascript/grid-ui/build";
  private static final String GRID_RESOURCE_WITH_PREFIX = String.format("/%s", GRID_RESOURCE);
  private final Route routes;
  public GridUiRoute() {
    URL uiRoot = GridUiRoute.class.getResource(GRID_RESOURCE_WITH_PREFIX);
    if (uiRoot != null) {
      ResourceHandler uiHandler = new ResourceHandler(new ClassPathResource(uiRoot, GRID_RESOURCE));
      HttpResponse uiRedirect = new HttpResponse()
        .setStatus(HTTP_MOVED_TEMP)
        .addHeader("Location", "/ui");
      routes = Route.combine(
        get("/").to(() -> req -> uiRedirect),
        get("/grid/console").to(() -> req -> uiRedirect),
        Route.prefix("/ui").to(Route.matching(req -> true).to(() -> uiHandler)));
    } else {
      LOG.warning("It was not possible to load the Grid UI.");
      Json json = new Json();
      routes = Route.matching(req -> false).to(() -> new NoHandler(json));
    }
  }
  @Override
  public boolean matches(HttpRequest req) {
    return routes.matches(req);
  }
  @Override
  public HttpResponse execute(HttpRequest req) {
    return routes.execute(req);
  }
}