@Override
    public void render(final Context context,
                       final R row,
                       final SafeHtmlBuilder sb) {
        if (row == null) {
            sb.append(SafeHtmlUtils.EMPTY_SAFE_HTML);
        } else {
            final String className = "svgCell-icon svgCell-button";
            sb.append(SvgImageUtil.toSafeHtml(svgPreset, className));
        }
    }
A cell containing an icon (ellipses icon by default) that when clicked
will execute an action. Useful for a simple

@param <R>
stroom-core-client-widget/src/main/java/stroom/cell/info/client/ActionCell.java