fix(create-element): inline demo subresources

[bennypowers]

What I did

1. update the generator's demo templates, removing the demo.css and ${elementName}.js subresources, and inlining them to the HTML instead.

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: 48a0b247b4d450a554af10ea2f25655f1c8a1353

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

| Name | Type | | -------------------------- | ----- | | @patternfly/create-element | Patch |

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