Support the new polyfill-support.js from Lit v2

[abdonrd]

Lit v2 has a new polyfill-support.js.

We need to include the web components polyfills like:

<script src="node_modules/lit/polyfill-support.js"></script>
<script src="node_modules/@webcomponents/webcomponentsjs/webcomponents-loader.js"></script>
<!-- Load application code here -->

[abdonrd]

Meanwhile, in the @open-wc/building-rollup, we should use customize the @open-wc/rollup-plugin-polyills-loader, right?

• https://open-wc.org/docs/building/rollup/#customize-polyfills
• https://lit.dev/docs/releases/upgrade/

polyfillsLoader: {
  polyfills: {
    custom: [
      {
        name: 'lit-polyfill-support',
        path: 'node_modules/lit/polyfill-support.js',
        test: "!('attachShadow' in Element.prototype)",
        module: false,
      },
    ],
  },
},

[abdonrd]

Example here: IBM/pwa-lit-template@349c59c