feat: provide an option to load the remoteEntry.json via a deploy url

[WvKuipersVisma]

This changes allows to provide a deployUrl option when calling initFederation to load the remoteEntry.json file from a custom path or domain like so:

initFederation('/assets/federation.manifest.json', {deployUrl: './custom-root/'})
  .catch(err => console.error(err))
  .then(_ => import('./bootstrap'))
  .catch(err => console.error(err));

or:

initFederation('/assets/federation.manifest.json', {deployUrl: 'http://example.com'})
  .catch(err => console.error(err))
  .then(_ => import('./bootstrap'))
  .catch(err => console.error(err));

This is needed when you run the application on a path other then root or when you want to load the assets over a custom domain. (like an CDN)

Closes #866