Update korge-hello-world repo to use Korge 7.0.0-alpha1 release

- Use branch in repo: https://github.com/korlibs/korge-hello-world/tree/jobe-m/feat/update-to-korge-7
- Check if the example works
- Add more targets like JS, iOS, etc.

Start with the korge-hello-world repository on the jobe-m/feat/update-to-korge-7 branch and verify how it currently uses the Korge 7.0.0-alpha1 release. Check whether the example works, then determine what is needed to add targets such as JS and iOS; done means the example builds and runs for the supported targets.

Written by the indexing model from the issue text.