_prevNextButtonTemplate(label, pageNumber, namespace = 'lion') {
    return html`
      <li>
        <button
          aria-label=${this.msgLit(`${namespace}-pagination:${label}`)}
          @click=${() => this.__fire(pageNumber)}
        >
          ${this._prevNextIconTemplate(label)}
        </button>
      </li>
    `;
  }
Get next or previous button template.
This method can be overridden to apply customized template in wrapper.
@param {String} label namespace label i.e. next or previous
@param {Number} pageNumber page number to be set
@param {String} namespace namespace prefix for translations
@returns {TemplateResult} nav item template
@protected