Update TwaManifest.ts shortcut comment

[hslee2008]

Describe the issue
The shortcuts attribute is not working and the comments on how to do this is also wrong.

 * shortcuts: [
 *      // Insert shortcuts here, for example:
- *      // [name: 'Open SVG', short_name: 'Open', url: '/open', icon: 'splash']
+ *      // { name: 'Open SVG', shortName: 'Open', url: '/open', chosenIconUrl: 'https://example.com/example.svg' }
 *  ],

1. The comment above should actually be an object rather than an array.
2. There should be chosenIconUrl according to the cli.
3. It should be shortName not short_name as it creates errors.

C:\Users\USER\AppData\Roaming\npm\node_modules\@bubblewrap\cli\node_modules\@bubblewrap\core\dist\lib\util.js:299
    return input.replace(/[\\']/g, '\\\\\\$&');
                 ^

TypeError: Cannot read properties of undefined (reading 'replace')
    at Object.escapeGradleString (C:\Users\USER\AppData\Roaming\npm\node_modules\@bubblewrap\cli\node_modules\@bubblewrap\core\dist\lib\util.js:299:18)
    at ShortcutInfo.toString (C:\Users\USER\AppData\Roaming\npm\node_modules\@bubblewrap\cli\node_modules\@bubblewrap\core\dist\lib\ShortcutInfo.js:49:35)
    at C:\Users\USER\AppData\Roaming\npm\node_modules\@bubblewrap\cli\node_modules\@bubblewrap\core\dist\lib\TwaManifest.js:205:67
    at Array.map (<anonymous>)
    at Object.generateShortcuts (C:\Users\USER\AppData\Roaming\npm\node_modules\@bubblewrap\cli\node_modules\@bubblewrap\core\dist\lib\TwaManifest.js:205:37)
    at eval (lodash.templateSources[0]:34:11)
    at TwaGenerator.applyTemplate (C:\Users\USER\AppData\Roaming\npm\node_modules\@bubblewrap\cli\node_modules\@bubblewrap\core\dist\lib\TwaGenerator.js:179:55)

Node.js v18.13.0

[andreban]

Thanks for catching this and sending over a PR. LGTM.